WO2013163589A2 - Modes de réalisation d'un dispositif à émission de champ - Google Patents

Modes de réalisation d'un dispositif à émission de champ Download PDF

Info

Publication number
WO2013163589A2
WO2013163589A2 PCT/US2013/038476 US2013038476W WO2013163589A2 WO 2013163589 A2 WO2013163589 A2 WO 2013163589A2 US 2013038476 W US2013038476 W US 2013038476W WO 2013163589 A2 WO2013163589 A2 WO 2013163589A2
Authority
WO
WIPO (PCT)
Prior art keywords
anode
cathode
suppressor
electric potential
gate
Prior art date
Application number
PCT/US2013/038476
Other languages
English (en)
Other versions
WO2013163589A3 (fr
Inventor
Jesse R. CHEATHAM, III
Philip Andrew Eckhoff
William Gates
Roderick A. Hyde
Muriel Y. Ishikawa
Jordin T. Kare
Nathan P. Myhrvold
Tony S. PAN
Robert C. Petroski
Clarence T. Tegreene
David B. Tuckerman
Charles Whitmer
Lowell L. Wood, Jr.
Victoria Y.H. Wood
Original Assignee
Elwha Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US13/545,504 external-priority patent/US9018861B2/en
Priority claimed from US13/587,762 external-priority patent/US8692226B2/en
Priority claimed from US13/666,759 external-priority patent/US8946992B2/en
Priority claimed from US13/774,893 external-priority patent/US9171690B2/en
Priority claimed from US13/790,613 external-priority patent/US8970113B2/en
Priority claimed from US13/860,274 external-priority patent/US8810131B2/en
Priority claimed from US13/864,957 external-priority patent/US8810161B2/en
Application filed by Elwha Llc filed Critical Elwha Llc
Priority claimed from US13/871,673 external-priority patent/US8928228B2/en
Publication of WO2013163589A2 publication Critical patent/WO2013163589A2/fr
Publication of WO2013163589A3 publication Critical patent/WO2013163589A3/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements or of ion traps common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H01J3/027—Construction of the gun or parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J45/00—Discharge tubes functioning as thermionic generators

Definitions

  • the present application is related to and/or claims the benefit of the earliest available effective filing date(s) from the following listed application(s) (the "Priority Applications"), if any, listed below (e.g., claims earliest available priority dates for other than provisional patent applications or claims benefits under 35 USC ⁇ 1 19(e) for provisional patent applications, for any and all parent, grandparent, great- grandparent, etc. applications of the Priority Application ⁇ )).
  • the present application is related to the "Related Applications,” if any, listed below.
  • APRIL 2012 with attorney docket no. 0910-006-001 -PR0002, is related to the present application.
  • CIP001 is related to the present application.
  • an apparatus comprises: a. cathode; an anode, wherein the anode and cathode are receptive to a first power source to produce an anode electric potential higher than a cathode electric potential: a. gate positioned between the anode and the cathode, the gate being receptive to a second power source to produce a gate electric potential selected to induce emission of a first set of electrons from the cathode; a suppressor positioned between the gate and the anode, the suppressor being receptive to a third power source to produce a suppressor electric potential selected to provide a force on an electron in a. direction pointing towards the suppressor in a region between the suppressor and the anode: and at least one element arranged to at least partially determine a trajectory of each of the electrons in the first set of electrons between the cathode and the anode.
  • a method corresponding to an apparatus including a cathode region, a gate region, a suppressor region, and an anode region comprises: applying an anode electric potential to the anode region that is greater than a cathode electric potential of the cathode region; applying a gate electric potential to the gate region to release a set of electrons from the cathode region; passing the set of electrons from the gate region to the suppressor region; applying a suppressor electric potential to decelerate the set of electrons between the suppressor region and the anode region; inductively coupling the set of electrons to produce electromagnetic energy; and binding the set of electrons in the anode region.
  • an apparatus comprises: a cathode; an anode, wherein the anode and cathode are receptive to a first power source to produce an anode electric potential higher than a cathode electric potential; a gate positioned between the anode and the cathode, the gate being receptive to a second power source to produce a gate electric potential selected to induce emission of a first set of electrons from the cathode; a suppressor positioned between the gate and the anode, the suppressor being receptive to a third power source to produce a suppressor electric potential selected to provide a force on an electron in a direction pointing towards the suppressor in a region between the suppressor and the anode; and circuitry operably connected to at least one of the cathode and the anode to control an output of the anode.
  • gate electric potential selected to induce emission of a first set of electrons from the cathode
  • a suppressor positioned between the gate and the anode, the suppressor being receptive to a third power source to produce a suppressor electric potential selected to provide a force on an electron in a direction pointing towards the suppressor in a region between the suppressor and the anode.
  • FIG. 1 is a schematic of an apparatus comprising a cathode, a gate, a
  • FIG. 3 is a schematic of an apparatus comprising a cathode, a gate, a
  • FIG. 4 is a schematic of an apparatus comprising a cathode, a gate, a
  • FIGS. 5-6 are flow charts depicting methods.
  • FiGS. 7-8 are graphs of thermodynamic efficiency versus power for a heat engine.
  • FIG. 9 is a schematic of a portion of a field emission device including a thin film.
  • FIG. 10 is a schematic of a field emission device having a cathode and anode that form a substantially interlocking structure.
  • FIG. 12 is a schematic of a field emission device, wherein the anode includes a thin coating.
  • FIG. 13 is a schematic of a field emission device having a gate and suppressor that are fabricated on a first substrate, and having a cathode and anode that are fabricated on a second substrate.
  • FIG. 14 is a schematic of a field emission device having a cathode, anode, and a gate/suppressor.
  • FIG. 15 is a schematic of the potential corresponding to the schematic of
  • FIG. 16 is a schematic of a back-gated field emission device.
  • FIG. 18 is a schematic of an anode and a suppressor with an electric field.
  • FIG. 19 is a schematic of a field emission device including spacers.
  • FIGS. 20-21 are flow charts depicting methods.
  • FIG. 22 is a schematic of a field emission device including a shadow grid.
  • FIG. 23 is a schematic of a field emission device including a control grid.
  • FIG. 24 is a schematic of a field emission device including an inductive
  • an apparatus 100 comprises a cathode 102, an anode 108 arranged substantially parallel to the cathode 102, wherein the anode 108 and cathode 102 are receptive to a first power source 1 10 to produce an anode electric potential 202 higher than a cathode electric potential. It is the convention in this discussion to generally reference electric potentials relative to the value of the cathode electric potential, which in such circumstances can be treated as zero.
  • the anode electric potential 202 and other electric potentials corresponding to the apparatus of FIG. 1 are shown in FIG. 2 for an embodiment of FIG . 1
  • the apparatus 100 further comprises a gate 104 positioned between the anode 108 and the cathode 502, the gate 104 being receptive to a second power source 112 to produce a gate electric potential 204, wherein the gate electric potential 204 is selected to induce electron emission from the cathode 102 for a first set of electrons 206 having energies above a first threshold energy 208.
  • both the cathode 102 and the anode 108 are electron emitters, and either or both of the cathode 102 and/or the anode 108 may include field emission enhancement features 103.
  • FIG. 1 shows the cathode 102 having a field emission enhancement feature
  • the apparatus 100 includes at least one region including gas through which at least a first portion of the first set of electrons 206 pass.
  • the region between the cathode 1 02 and anode 108 is a gas-filled region (or, spacer region) through which at least a portion of the first set of electrons 206 passes.
  • the gas may be comprised of at least one atomic or molecular species, partially ionized plasma, fully ionized plasma, or mixtures thereof.
  • the gas composition and density may be chosen to be conduci ve to the passage of electrons.
  • the gas density may be below atmospheric density, and may be sufficiently low as to be effectively a vacuum.
  • This region may, in some embodiments, be air or its equivalent, wherein the pressure of the region may or may not be adjusted.
  • the resulting potential 215 as a function of distance from the cathode in the x- direction 126 in the apparatus 100 is shown in FIG. 2 for an embodiment of FIG. 1 corresponding to a heat engine.
  • the potential 215 does not take into account the space charge electric potential due to the emitted electrons between the cathode and anode. It also does not take into account the image charge electric potential due to image charge effects of a flat plate (i.e., the cathode and anode).
  • the net electric potential 216 experienced by the electrons between the cathode and anode is a.
  • electrons obey the laws of quantum mechanics and therefore, given a potential barrier such as that formed between the cathode and gate (i.e., the portion of the potential 216 that is between the cathode and gate), electrons having energies between the bottom and top of the potential barrier have some probability of tunneling through the barrier. For example, some electrons having energies above the threshold energy 208 may not be emitted from the cathode 102.
  • first, second and third power sources 1 10, 1 52 and 1 14 are shown in FIG. 1 as being different, in some embodiments the power sources 1 10, 1 12 and 1 14 may be included in the same unit. There are many different ways that the power sources 1 10, 1 12 and 1 14 may be configured relative to the elements 502, 104, 106 and 108, and one skilled in the art may determine the configuration depending on the application.
  • Electrons in a reservoir (e.g., the cathode 102 and anode 108) obey the Fermi- Dirac distribution:
  • ⁇ ⁇ is the cathode Fermi energy 214 and ⁇ ⁇ is the anode Fermi energy 220 shown in FIG. 2, measured from the bottom of the conduction band of the cathode 102, and T c is the cathode temperature and T a is the anode temperature.
  • the Carnot-efficiency energy E carnot is the energy at which the Fermi occupation of the cathode 102 and the anode 108 are equal, and theoretically electron flow between the two occurs without change in entropy. Absent potential barrier 216, at any given electron energy above E carnot there are more electrons in the hotter plate, so the net flo w of electrons at these energies go from hot plate to cold plate. Con versely, at any given electron energy below E canio! there are more electrons in the colder plate, so the net flow of electrons at these energies go from cold plate to hot plate.
  • the cathode 102 is hotter than the anode 108 (2 c > T a ) and the anode 108 is biased above the cathode 102 as shown in FIG. 2.
  • ⁇ ⁇ ⁇ + Vo, where Vo is the anode electric potential 202.
  • the Carnot-efficiency energy is equal to:
  • V carnot is the Carnot efficiency. Due to the potential bias Vo, every electron going from the cathode 102 to the anode 108 gains useful potential energy V 0 that can be used to do work, and every electron going from the anode 108 to the cathode 102 expends potential energy Vo to transport heat instead.
  • the gate electric potential E g (204) is slightly below the Camot-efficiency energy E carnot or
  • the suppressor electric potential E s (210) may be selected to be the same as the gate electric potential E g (204).
  • the apparatus 100 is a nanoscale device.
  • the cathode 102 and anode 108 may be separated by a distance 122 that is 1 0-1 000 nm
  • the cathode 102 and gate 104 may be separated by a distance 1 16 that is 1 -100 nrn
  • the anode 108 and the suppressor 106 may be separated by a distance 120 that is 1 -100 nm.
  • the apparatus is larger than nanoscale, and exemplary separation distances 1 16, 1 18, 120, and/or 122 may range between the nanometer to millimeter scale.
  • this scale is again exemplary and not limiting, and the length scales 1 16, 1 18, 120, 122 may be selected at least partially based on operating parameters of other gridded electron emitting devices such as vacuum tubes.
  • the cathode and anode work functions 213, 219 are determined by the material of the cathode 102 and anode 108 and may be selected to be as small as possible.
  • the cathode and anode may comprise different materials.
  • One or both materials can include metal and'or semiconductor, and the material(s) of the cathode 102 and/or anode 108 may have an asymmetric Fermi surface having a preferred Fermi surface orientation relative to the cathode or anode surface.
  • An oriented asymmetric Fermi surface may be useful in increasing the fraction of electrons emitted normally to the surface and in decreasing the electron's transverse momentum and associated energy.
  • This reduction may utilize an asymmetric Fermi surface which reduces momentum components normal to the surface.
  • This reduction may involve minimization of the material's density of states (such as the bandgap of a semiconductor) at selected electron energies involved in the device operation.
  • the device as shown in FIG. 1 may be configured, for example, as a heat pump or a refrigerator.
  • the bias VQ is applied to the cathode 102 instead of to the anode 108 as shown in FIG. 2.
  • the bias Vo (202) is applied to the anode and the suppressor electric potential 210 and gate electric potential 204 may be chosen to be substantially below the Camot-efficiency energy E carm>j , In this case, net current flow and heat transport is from the anode to the cathode..
  • the apparatus 100 further includes a screen grid 302 positioned between the gate 104 and the suppressor 106, the screen grid 302 being receptive to a fourth power source 304 to produce a screen grid electric potential.
  • the screen grid electric potential can be chosen to vary the electric potential 216 between the gate 104 and the suppressor 106, and to accelerate electrons to another spatial region and thus reduce the effects of the space charge electric potential on the field emission regions of the cathode and/or anode.
  • the apparatus 100 may further comprise a meter 404 configured to measure a current at the anode 108, and wherein the circuitry 402 is responsive to the measured current to vary at least one of the first, gate and suppressor electric potentials 202, 204 and 210.
  • the apparatus 100 may further comprise a meter 406 configured to measure a temperature at the anode 108, and wherein the circuitry 402 is responsive to the measured temperature to vary at least one of the anode, gate and suppressor electric potentials 202, 204 and 210.
  • the apparatus 100 may further comprise a meter 408 configured to measure a temperature at the cathode 102, and wherein the circuitry 402 is responsive to the measured temperature to vary at least one of the anode, gate and suppressor electric potentials 202, 204 and 210.
  • the circuitry 402 may be configured to iteratively determine optimal cathode 102 and anode 108 temperatures. For example, as described above relative to electric potentials, the circuitry 402 may be operably connected to the meter 404 configured to measure a current at the anode 108, and may iteratively change one of the cathode 102 and anode 108 temperatures to maximize the current at the anode 108.
  • the gate and suppressor electric potentials 204, 210 may be varied as a function of time.
  • the gate electric potential 204 may be switched on to release the first set of electrons 206 from the anode, and switched off once the first, set of electrons 206 has passed through the gate 104.
  • the suppressor electric potential 210 may be switched on to accelerate the first set of electrons 206 towards the anode 108, and switched off once the first set of electrons 206 has passed through the suppressor 106.
  • Such an embodiment assumes high switching speeds. In some embodiments, switching such as that described above occurs cyclically and responsive to the circuitry 402.
  • a method comprises: (502) applying a gate electric potential 204 to selectively release a first set of electrons 206 from a bound state in a first region (where in one embodiment the first region corresponds to the cathode 102); (504) applying a suppressor electric potential 250 to selectively release a second set of electrons from emission from a bound state in a second region different from the first region, the second region having an anode electric potential that is greater than a cathode electric potential of the first region (where in one embodiment the second region corresponds to the anode 108), the second region having an anode electric potential 202 that is greater than a cathode electric potential of the first region; and (506) passing a portion of the first set of electrons 206 through a gas-filled region and binding the passed portion of the first set of electrons 206 in the second region.
  • FIGS. 1 -4 Various methods have been described herein with respect to FIGS. 1 -4 and may apply to the methods depicted in the flow chart of FIG. 5. For example, methods related to the circuitry 402 and another apparatus shown in FIG. 4 apply to the method of FIG. 5, where the first region includes at least a portion of the cathode 102 and the second region includes at least a portion of the anode 108.
  • a method comprises (602) receiving a first signal corresponding to a heat engine, the heat engine including an anode, cathode, gas-filled region, gate and suppressor; (604) processing the first signal to determine a first power output and/or relative thermodynamic efficiency of the heat engine as a. function of an anode electric potential, a gate electric potential, and a suppressor electric potential; (606) producing a second signal based on a second power output and/or thermodynamic efficiency greater than the first power output and/or thermodynamic efficiency; and (608) transmitting the second signal corresponding to the second power output and/or thermodynamic efficiency.
  • the first signal includes a measured parameter such as a current at the anode 108, where the electric potentials are varied to optimize the current at the anode.
  • producing the second signal may further include determining a change in at least one of the anode, gate and suppressor potentials, and the method may further comprise varying at least one of the anode, gate, and suppressor potentials in response to the determined change.
  • producing the second signal may further include determining a change in at least one of a cathode and an anode temperature, and the method may further comprise varying at least one of the cathode and anode temperatures in response to the determined change.
  • the anode, cathode, gate, and suppressor are separated by cathode-gate, gate-suppressor, and suppressor-anode separations
  • producing the second signal may include determining a change in at l east one of the cathode-gate, gate-suppressor, and suppressor-anode separations, and the method may further comprise varying at least one of the cathode-gate, gate-suppressor, and suppressor- anode separations in response to the determined change.
  • the received first signal corresponds to an anode current
  • processing the first signal to determine a first relative thermodynamic efficiency of the heat engine as a function of an anode electric potential, a gate electric potential, and a suppressor electric potential includes determining the relative thermodynamic efficiency based on the anode current.
  • the "relative power output,” and/or “relative thermodynamic efficiency” may be an actual power output and/or thermodynamic efficiency or it may be a quantity that is indicative of the power output and/or thermodynamic efficiency, such as the current at the anode.
  • the relative power output and relative thermodynamic efficiency represent performance characteristics of the heat engine.
  • T c and T a are the temperatures of the cathode and anode
  • the potential barrier (216) that is created between the cathode and anode only filters electrons with respect to their momentum in the x-direcfion (126), not with respect to their total momentum.
  • the current density J(W) as a function of energy W in the x-direcfion (126) is:
  • W is the electron energy associated with the component of momentum in the x-direction (126), which we will call the normal energy, and is defined by: W - ⁇ - ⁇ - + V(x)
  • V(x) is the net electric potential 216.
  • D(W) is the transmission function and represents the probability that an electron inside the emitter (for the heat engine, both the cathode and anode are emitters) with normal energy W either crosses over or tunnels through the energy barriers defined by the net electric potential (216).
  • WKB Wentzel-Kramers-Briilouin
  • V(x) is the net electric potential (216)
  • m is the mass of an electron
  • the potential of a single field emission barrier (e.g., one of the peaks of the net electric potential (216) forms a single field emission barrier) is of the form:
  • V SB (x) ⁇ - eFx
  • N(W)dW is the electron supply function and describes the number of electrons incident on the emitter surface per second per unit area with normal energy inside the interval defined by Wand W+clW. For a metal, this is:
  • J ne! (JV)dW N C (W) - N° (W)]D(W)dW
  • D(W) is the tunneling transmission coefficient that takes into account both barriers formed by the net electric potential 216. Denoting the barrier between the cathode and gate as D SB (W) and the barrier between the anode and suppressor as DsB a (W), and taking reflections into account, D(W) is given by:
  • D(W) is approximately:
  • the gate (104) and suppressor (106) are set at the same potential bias V ⁇ , it is reasonable to assume that the electrons are uniformly distributed in the cathode- anode gap, with constant space charge density p.
  • the space charge potential will be shaped like a parabola (and therefore, the portion of (216) between the gate (104) and the suppressor (106) will be a parabola), with its peak in the middle of the gap between the cathode (102) and anode (202), and a peak height AW, iC thd' t is offset from V grid by: ep d "
  • d is the distance between the cathode and anode. Electrons with energies lower than this peak will find the space charge potential difficult to travel through.
  • Electrons with energies below WB are assumed to have a transmission probability of zero:
  • 0(W) is the Heaviside step function.
  • WB is a function of , but the charge density p(W) as a function of the normal energy W depends on the sum of the cathode-emitted and anode-emitted current: p(W)dW J, » jw dw ⁇ m
  • W + kT is the total energy of the emitted electron, including the kinetic energy in all directions, and we assume that the replacement electron comes in at, the Fermi energy //..
  • the cathode (102) should be losing heat energy while the anode should be receiving some heat, hence Q c > 0 and 0 : - 0 .
  • thermodynamic efficiency ⁇ is the ratio between work gained to heat used, or, equivatingly, the ratio of the useful power gained ( J ttet V 0 ) to the total heat flux ⁇ Q O!KE , ) ' -
  • Figure 7 corresponds to a cathode (102) and an anode (108) having field emission enhancement features ( 103), such that ⁇ > ⁇ .
  • Figure 7 shows how the thermodynamic efficiency and power of a heat engine are related. By graphing this relationship the tradeoffs between thermodynamic efficiency and power are illustrated.
  • the applied anode bias may be selected to maximize the thermodynamic efficiency, or it may be selected to maximize the power, or the anode electric potential 202 may be selected to correspond to some other point on the graph, such as between the maximum thermodynamic efficiency and the maximum power.
  • a graph such as Figure 7 (or simply the corresponding data) may be created.
  • a user may want to select the applied voltage Vo based on a maximum thermodynamic efficiency, power, or optimal but not necessarily maximized values for each.
  • the temperature of the cathode 102 and/or anode 108 may be determined by the operating conditions of the device such as ambient temperature and/or a temperature of the heat source that provides heat to the cathode. Further, these values may change in time. Therefore, in embodiments where the operating conditions determine the values of one or more parameters of the heat engine, other values may be selected to optimize the performance of the heat engine for the given parameters.
  • the anode electric potential 202 may be selected according to optimal values of thermodynamic efficiency and power as shown in Figure 7, and the thermodynamic efficiency and power calculated as a function of varying gate and suppressor electric potentials 204, 2 0.
  • Figure 8 shows the thermodynamic efficiency plotted versus power for varying gate and suppressor electric potentials 204, 210.
  • the cathode temperature r c 1000 K
  • the anode temperature ⁇ 300
  • the work functions of the cathode and anode ⁇ 2 ⁇ eV
  • the cathode-anode separation (122) is 50 am
  • the cathode-gate separation (1 16) and the suppressor-anode separation 120 are both 2 nm
  • the anode electric potential 202 is 4k(T c - T a ) .
  • thermodynamic efficiencies and/or according to the calculated first and second relative power outputs are thermodynamic efficiencies and/or according to the calculated first and second relative power outputs.
  • a method of the embodiment as described above may be employed when, for example, a device including a heat engine is received and the device has been manufactured with a substantially fixed cathode-gate separation (1 16), suppressor- anode separation (120), and/or cathode-anode separation (122). Or, in some embodiments, the device may not yet have been manufactured but some parameters of the device may be fixed for other reasons. Determining the substantially fixed parameters may include measuring the parameters, receiving the parameters (wherein the parameters may be, for example, listed on the device, provided in a computer program, or provided in a different way), or determining the fixed parameters in a different way.
  • the substantially fixed parameters may include a cathode and/or anode field enhancement factor (or, more generally, a cathode and/or anode geometry).
  • the substantially fixed parameters may further include the cathode work function (213), anode work function (21 9), cathode and anode band structures, and/or cathode and anode emissivities.
  • the relative power output and/or the relative thermodynamic efficiency may be calculated for one or more variable parameters, and the one or more variable parameters may be selected according to a chosen value for the relative power output and'or relative
  • the gate (104) and/or the suppressor (106) may include a thin film (904), as shown in FIG. 9 (FIG. 9 shows an embodiment with a cathode (102), dielectric (902), and thin film (904) that forms the gate (104), however a similar embodiment includes an anode (108), dielectric (902), and thin film (904) that forms the suppressor (106)), where the thin film (904) may be metal and/or graphene, and where graphene may be a single layer or a Mayer film.
  • the graphene may, in some embodiments, include a graphene allotrope, doped graphene, and/or functional ized graphene.
  • the thin film (904) may be fabricated by depositing the dielectric (902) on the cathode (102) and/or anode (108), then depositing the thin film (904) of metal or graphene that, forms the gate (104) and/or suppressor (106).
  • the dielectric (902) can be at least partially etched away, or in other embodiments it may be left in place.
  • These emitters include a metal or semiconductor base electrode, an insulator, and a thin top electrode serving as the gate/suppressor.
  • FIG. 9 shows a single thin film (904) that forms the gate ( 104), in some embodiments two or more thin films such as the film (904) may form the gate.
  • the gate (104) and/or suppressor (106) may be a thin film as described with respect to FIG. 9, or the gate (104) and/or the suppressor (506) may have a different configuration.
  • the dielectric (902) may be used to support the gate (104) and/or suppressor (106), and/or it may serve to maintain the separation between the cathode (102) and gate (104) and/or the separation between the anode (108) and suppressor (106).
  • the dielectric (902) may be silicon oxide (SiO?), boron nitride, diamond, and/or a self-healing dielectric, e.g., glassy rather than crystalline materials.
  • At least one of the cathode (102) and anode (108) includes at least one of: tungsten, fhoriated tungsten, an oxide-coated refractory metal, a boride, lanthanum hexaboride, molybdenum, tantalum, and hafnium.
  • the cathode (102) may include thoriated tungsten, which has a work function of approximately 2.5 eV. When heated, the lower-work- function thorium in the material migrates to the surface.
  • the cathode (102) includes an oxide-coated refractory metal, which has a work function of approximately 2 eV
  • the cathode (102) includes a boride having a work function of approximately 2.5 eV.
  • borides such as lanthanum, hexaboride are amenable to physical vapor deposition techniques, a d the cathode may be relatively easily coated with these materials.
  • a material with a relatively low work function such as diamond-like carbon (DLC) may be incorporated as a coating for the cathode (.102).
  • DLC diamond-like carbon
  • the DLC may be doped with nitrogen. DLC is amenable to low temperature deposition techniques, and may be directly coated on Spindt tips, for example.
  • At least one of the cathode (102) and anode (108) includes diamond, and, in particular, may be coated with diamond.
  • a diamond coating can be deposited from a methane atmosphere. Pure diamond has a relatively high work function, however diamond can be doped (with, for example, hydrogen) to have a low work function, and may be especially useful at relatively low operating temperatures. Hydrogen-terminated diamond surfaces have been found to exhibit negative electron affinity (NEA). To further increase field emission with diamond coatings, the diamond may be selected to have small grain sizes, or nano-crystalline diamond may be used. To take full advantage of the N EA of diamond at relatively low applied fields, the diamond may be n-type doped to place its Fermi level close to the conduction band.
  • pure diamond can withstand electric field stresses up to about 1-2 V/nm before dielectric breakdown commences, it may be used as the dielectric to support the gate (104) and/or suppressor (106) relative to the anode ( 102) and/or the cathode (108).
  • the cathode (102) and/or the anode (108) may include one or more carbon nanotubes that serve as field emission enhancement feature(s) (103), There may be a single nanotube serving as a single field emission
  • multiple nanotubes sometimes called nanotube forests
  • individual nanotubes may be selectively ablated to control emission.
  • one or more carbon nanobuds may sen'e as one or more field emission enhancement feature(s) (103).
  • the cathode (102) and/or the anode may include a semiconductor, which may include silicon.
  • the semiconductor may be doped. Specifically, doping the semiconductor may change its density of states, and so a semiconductor may be doped according to a selected density of states.
  • a semiconductor cathode (102) and/or anode (108) may further be coated in order to vary the electron affinity and/or the work function, and/or to optimize the
  • the semiconductor may further be doped to vary the electron affinity, in some cases producing negative electron affinity (NEA) material.
  • NAA negative electron affinity
  • the cathode (102) and anode (108) may form a substantially interlocking structure ("interlocking combs"), as shown in FIG. 10.
  • interlocking combs substantially interlocking structure
  • the gate (104) and the suppressor (106) are shown as being substantially continuous, however in some embodiments they may be discontinuous.
  • the spacings in the gate (504) and suppressor (106) shown in FIG. 10 are largely symbolic, and may be oriented differently according to a particular embodiment.
  • the comb structure of the cathode (502) and anode (508) are relatively large in comparison with the size of a field emission enhancement structure (103), and an embodiment that employs such a comb structure may also include one or more field emission enhancement structures (103), although these are not shown in FIG. 10.
  • FIG. 10 shows a cathode (102) having a spatially- varying slope, and an anode (108) also having a spatially varying slope that is complementary to the spatially-varying slope of the cathode (102).
  • the spatially-varying slopes of the cathode (102) and anode (108) shown in FIG. 10 are substantially periodic, however in other embodiments they may be a-periodic and/or quasi-periodic.
  • the slope of the cathode (102) and/or the slope of the anode (108) may be more smoothly varying that what is shown in FIG, 10, As shown in FIG. 10, the cathode-anode separation (122) varies slightly, however this separation is minimized.
  • the cathode-anode separation (122) is substantially constant. In other embodiments, the cathode-anode separation (122) may ha ve greater spatial variations, or in the case where the cathode (102) and anode (108) are substantially sinusoidal, the cathode-anode separation (122) may be configured with very little spatial variation.
  • the cathode (102) and anode (108) are substantially tubular, wherein at least a portion of the anode (108) is substantially circumscribed by at least a portion of the cathode (102).
  • electrons flow radially from the cathode (102) to the anode (108), and vice-versa.
  • the cathode (102) and anode (108) are shown as being substantially cylindrical in FIG. 1 1 , in some embodiments there may be deviations from the cylindrical structure (i.e., they may be dented, their cross-sections may be an n-gon such as a hexagon or octagon, or they may form a different type of substantially coaxial structure).
  • cathode (502) may form the inner structure and the anode (108) may form the outer structure.
  • a coolant or heating structure may be placed inside the inner structure (for example, where the anode (1 08) forms the inner structure of a heat engine, a coolant may be configured to flow through or proximate to the anode (108), or where the cathode (102) forms the inner structure of a heat engine, a heating mechanism such as a heated fluid may be configured to flow through or proximate the cathode (102)).
  • the gap between the cylinders as shown in FIG. 1 1 may change as a function of the temperature of the cylinders.
  • the gate (104) and suppressor ( 106) are not shown in FIG. 1 1 for clarity, in most embodiments of a heat engine at least one grid would be included.
  • a thin dielectric coating (1202) is included on the anode (108).
  • the thin dielectric coating may, in some embodiments, include a negative electron affinity (NEA) material such as hydrogen terminated diamond, which may be deposited on a metal that forms the anode (108).
  • NAA negative electron affinity
  • Such an embodiment may lower the effective work function of the metal that forms the anode (108).
  • This embodiment may or may not include the suppressor (106).
  • the NEA material forms the anode (108), and in this embodiment the suppressor (106) may not be included and the device may still function as a. heat engine.
  • the NEA material may be chosen or doped such that its electron quasi-Fermi level is close to the conduction band.
  • one or more of the gate (104) and suppressor (106) may be at least partially coated with one or more insulating materials.
  • all or part of the apparatus may he fabricated, e.g. via lithography, on a substrate.
  • the cathode (102), gate (104), suppressor (106), and the anode (108) are formed via lithography on a substrate such that they are all substantially one-dimensional and coplanar.
  • the gate (104) and the suppressor (106) are fabricated on a first substrate (1302) and the cathode (102) and anode (108) are fabricated on a second substrate (1304), wherein the first and second substrates (1302, 1304) are then positioned such that together the elements (1302, 1304, 1306, 1308) form the field emission device.
  • the gate (104) and the suppressor (106) are effectively insulated from the cathode (102) and the anode (108) by the second substrate (1304).
  • different elements such as (1302, 1304, 1306, 1308) may each be fabricated on their own substrate.
  • insulators or other materials may be incorporated according to the particular embodiment.
  • more or fewer elements such as (1302, 1304, 1306, 1308) may be incorporated in the designs.
  • the gate (104) and the suppressor (106) may be created with a single grid, as shown in FIG. 14.
  • the resulting potential (1502) as a function of distance from the cathode in the x-direction 126 is shown in FIG. 15 for the embodiment shown in FIG. 14,
  • This embodiment is similar to that of FIG. I, but having a single grid (the gate/suppressor 1402) that replaces the gate (104) and the suppressor (106),
  • the gate/suppressor (1402) is placed close enough to the anode (108) to be able to induce electron emission from the anode (108).
  • a gated field-emitter array such as a Spindt array is fabricated to produce the cathode (102) and the gate/suppressor (1402), and an anode (108) is arranged proximate to the gate/suppressor (1402).
  • the gate/suppressor (1402) is supported on and proximate to the anode (108), and there is no additional grid structure supported on the cathode (102), although the cathode (102) may still have field-enhancement structures.
  • the field emission device is back-gated, as shown in FIG. 16.
  • the gate (104) and the suppressor (106) are not positioned between the cathode (102) and anode (108), rather, the cathode (102) and anode (108) are positioned between the gate ( 104) and suppressor (106).
  • the configuration of FIG . 16 is different in this way from the configuration of FIG. 1 , they both may be configured as heat engines, such that electrons are emitted from both the cathode (102) and anode (108) and produce a net flow of electrons from the cathode (102) to the anode (108).
  • FIG. 16 the gate (104) and the suppressor (106) are not positioned between the cathode (102) and anode (108), rather, the cathode (102) and anode (108) are positioned between the gate ( 104) and suppressor (106).
  • FIG. 16 the configuration of FIG. 16 is different in this way from the configuration of FIG. 1 , they both may be configured as heat engines
  • the 56 may include a dielectric layer between the gate (104) and cathode ( 102), and or between the anode (108 ) and suppressor (106).
  • the dielectric an example of a dielectric included between elements is shown in FIG. 9 may be continuous or discontinuous.
  • the apparatus as shown in FIG. 16 may be configured to reduce or remove accumulations of charge that may occur, for example, as a result of a dielectric layer. As described previously with respect to other embodiments described herein, there may be more or fewer elements than shown in FIG. 16.
  • FIG. 16 shows the order being gate (104), cathode (102), anode (108), suppressor (106). How r ever, in other embodiments the order may be gate (104), cathode (102), suppressor (106), anode (108). Or, the elements may be in a different order.
  • emission from the cathode (102) may be e hanced electro magnetically, as shown in FIG. 17.
  • FIG, 17 is shown with the configuration of FIG. 1 as an example, however any of the embodiments described herein may include enhanced cathode emission via electromagnetic energy.
  • FIG. 17 shows
  • This electromagnetic energy (1702) incident on the cathode (102) may be used to increase the number of electrons emitted, the rate of electrons emitted, and/or the energy of the emitted electrons from, the cathode (102), which may therefore increase the power density of the device.
  • the properties of the cathode (102) such as the cathode thickness, the cathode materials such as dopants, may be selected such that the photo-excited electrons tend to be emitted from the cathode (102) before they thermalize, or after they thermal ize in the conduction band.
  • FIG. 17 shows the electromagnetic energy ( 1702) hitting the cathode (102) at a single location, however in different embodiments the
  • the source of the electromagnetic energy ( 5702) includes, but is not limited to, solar and/or ambient electromagnetic energy, radiation from a local heat source, one or more lasers, and/or a different source of electromagnetic energy.
  • sources of electromagnetic energy that may be used in an embodiment such as that shown in FIG. 57 and one skilled in the art may select the source according to the particular embodiment.
  • the properties of the electromagnetic energy (1702) such as the frequency, polarization, propagation direction, intensity, and other properties may be selected according to a particular embodiment, and in some embodiments may be selected to enhance the performance of the device.
  • optical elements such as lenses, photonic crystals, mirrors, or other elements may be incorporated in an embodiment such as that shown in FIG. 17, for example, to adjust the properties of the electromagnetic energy.
  • the emission from the cathode ( 102) may be enhanced sufficiently such that the position and/or electric potentials applied to the gate (104) and/or suppressor (106) may be adjusted according.
  • the suppressor (106) and the anode (108) as shown and described with respect to FIGS. 1 and 2 may be incorporated in a different device, such as a different thermionic converter, a thermionic refrigerator, a photomultiplier, an electron multiplier, low energy electron detectors, or another device.
  • the suppressor (106) is placed proximate to the anode (108) (in the case of an electron multiplier, the anode (108) is usually called a dynode in conventional literature; however, for consistency with other embodiments the word anode is used herein), and the suppressor electric potential (210) and the anode electric potential (202) are selected such that the net electric field (1802) points from the anode (108) to the suppressor (106).
  • This electric field (1802) is configured such that an electron placed in the field experiences a force in a direction pointing away from the anode (108).
  • first threshold energy (208) there will be some possibility that the electrons can pass through the field (1 802) and to the anode (108), such as in the direction (1 806) as shown in FIG. 18.
  • the electrons (206) may be configured to bind to the anode ( 508) (such as in the embodiment of a heat engine) or the electrons may be configured to interact with the anode (108) to produce secondary electrons (such as in the embodiment of an electron multiplier).
  • the first set of electrons (206) are represented symbolically in FIG . 18 as a single object, one skilled in the art will understand that this is a simplified representation and that the actual transport and spatial distribution of electrons is more complex.
  • FIG. 18 is substantially two-dimensional and the field (1802) is shown as being substantially constant and pointing in one direction.
  • the field (1802) may vary in one, two, or three spatial dimensions, and/or the field may have components along each of the three dimensions.
  • the field may include edge effects (not shown) near the edge(s) of the suppressor.
  • the embodiment of FIG. 18 includes a segment of the embodiments described previously with respect to FIGS. 1 , 2, and other related figures that include the suppressor (106) and the anode (108 ). Therefore, the embodiment of FIG. 18 may be included in previously described embodiments and/or it may be incorporated in other, different embodiments than previously described, such as in an electron multiplier. Further, components as described previously herein such as the circuitry (402) and/or the meters (404, 406, 408) may also be included in the embodiment of FIG. 1 8.
  • the suppressor electric field (1802) may be varied.
  • the suppressor electric field (1802) may be varied based on
  • measurements of current, temperature, and/or other parameters may be varied substantially periodically or in a different way.
  • the suppressor electric field (1802) includes the net field between the anode (108) and the suppressor (106).
  • elements that produce an electric field which add together to produce an electric field such as (1802) that points away from the anode (108) (i.e., the electric field (1 802) provides a force on an electron in the direction of the electric field (1802)).
  • an electric potential may be applied to each of the cathode (102), gate (104), suppressor (106), and anode (108). There may even be additional elements having an applied electric potential.
  • an electric potential may be applied to each of the cathode (102), gate (104), suppressor (106), and anode (108).
  • the net effect of all of the electric fields produced by the electric potentials includes an electric field that is between the anode (108) and the suppressor (106) and has at least one component that points away from the anode (108) and to the suppressor ( 106) (where, again, the electric field provides a force on an electron in the direction of the electric fiel d (1 802)),
  • the device is a mechanical resonator, where the mechanical resonator is operably connected to an element in the apparatus to vary the pattern substantially periodically in response to the first signal.
  • the mechanical resonator may have a frequency, an amplitude, and/or other properties that are tunable responsive to the first signal.
  • the mechanical resonator may be configured to receive a signal from circuitry 402 to apply or remove power to the resonator, to tune the resonator, and/or to otherwise control the resonator in a different, way.
  • the apparatus includes a measurement device operably connected to at least one of the cathode, gate, suppressor, and anode, and configured to output the first signal.
  • the measurement device may be operably connected to the anode, gate, suppressor, and/or the cathode, wherein the first signal includes an output current at the anode, gate, and/or suppressor, and/or a temperature at the anode and/or cathode.
  • the circuitry 402 may process this signal and output a signal to vary the apparatus in some way, such as by moving one or more elements (102, 104, 106, 108) of the device relative to other elements (102, 104, 106, 108) in the device, by varying a mechanical resonator in some way as described previously, or it may vary the apparatus in a different way in order to change the operation of the device.
  • Such feedback may be continuous, where the measurement is performed on a continuous or nearly continuous basis.
  • the dimensions of the device can be tuned by varying the voltages applied to the elements (102, 104, 106, 108), i.e., the gate electric potential, suppressor electric potential, anode electric potential, or a different, potential applied to one or more of the elements (102, 104, 106, 108) of the device.
  • the separation between the elements (102, 104, 106, 108) may be adjusted according to an applied magnetic field.
  • permanent magnets may be configured relative to the device to apply a force to one or more of the elements (102, 104, 106, 108) in order to maintain separation distances between the elements (102, 504, 106, 108).
  • the magnetic field may be produced by an electromagnet, where the electromagnet may be operably connected to control circuitry 402 to vary the magnetic field produced by the electromagnet, in response to a user signal and/or to a measurement of one or more parameters of the apparatus.
  • one or more of the elements (102, 104, 106, 108) may be at least partially supported by a spacer, wherein the spacer has a positive or negative thermal expansion coefficient such that the pattern formed by the elements (102, 104, 106, 108) varies as a function of temperature.
  • the field enhancement feature may be configured with a thermal expansion coefficient that is less than that of the spacer, such that the field enhancement feature 103 does not extend beyond the gate (104) (in the case where the field enhancement feature is part of the cathode) and/or the suppressor (106) (in the case where the field enhancement feature is part of the anode).
  • the apparatus as described herein includes at least, one spacer (1902) that at least partially determines at least one of the cathode-gate separation (1 16), the suppressor-anode separation (120), the cathode- anode separation (122), and/or the gate-suppressor separation ( 18).
  • the apparatus includes, for example, several particles and a post that, are used to at least partially determine the cathode-gate separation (116), the suppressor-anode separation (120), and/or the cathode-anode separation (122).
  • the spacer (1902) may have other shapes and/or configurations.
  • the apparatus may include spacers similar to those shown in Figure 19, but sized and positioned such that they at least partially determine the gate-suppressor separation (1 18).
  • the spacers (1902) may have a different shape as that shown in Figure 19, such as an irregular shape.
  • the spacers may, in some embodiments, resemble a rail, or they may form a different
  • the spacer may include a layer of material deposited on one or more of the elements (102, 104, 106, 108), where the layer of material may have one or more channels etched to allow electron transport.
  • the apparatus includes a field enhancement feature (103), and in this case the spacer may be positioned to minimize interactions of electrons from the field enhancement feature with the spacer. For example, where the spacer includes a layer of material deposited on the cathode (102) and/or anode (108), the portion of material near the field enhancement feature may be etched away.
  • the spacer may include a. conductive material, and in such an embodiment the conductive material may be electrically isolated from the elements (102, 104, 106, 108), In some embodiments the spacer includes a material selected according to a mechanical strength, a thermal conductivity, dielectric strength, and/or secondary electron emission characteristics.
  • the spacer includes a coating that at least partially surrounds the spacer, wherein the coating includes a material selected according to an electrostatic property, where the material may he, for example, a metal oxide, a DLC film., an amorphous silicon, and/or silicon carbide.
  • the cathode region and the gate region are separated by a cathode-gate separation distance (1 16), and wherein changing the pattern includes changing the cathode-gate separation distance (1 16).
  • the suppressor region and the anode region are separated by a suppressor-anode separation distance (120), and wherein changing the pattern includes changing the suppressor-anode separation distance ( 120).
  • the cathode region and the anode region are separated by a cathode-anode separation distance (122), and wherein changing the pattern includes changing the cathode-anode separation distance (122).
  • the apparatus may include one or more measurement devices that are configured to measure a condition of the apparatus, such as a current and/or temperature, and change the pattern based on the measurement,
  • changing the pattern includes applying a resonator to one or more elements (102, 104, 106, 108) such as the gate (104) and/or the suppressor (106), and changing the pattern substantially periodically with the resonator.
  • a resonator to one or more elements (102, 104, 106, 108) such as the gate (104) and/or the suppressor (106), and changing the pattern substantially periodically with the resonator.
  • Such an embodiment may include tuning the resonator, either via user input or according to a different signal.
  • changing the pattern includes changing at least one of the gate electric potential, the suppressor electric potential, and the anode electric potential.
  • the electric potentials applied to the elements (102, 104, 106, 108) can vary the forces between the element and can slightly change the spacing between the elements (102, 104, 106, 108),
  • substantially maintaining the pattern includes substantially maintaining a pressure and/or a magnetic field corresponding to the cathode region, gate region, suppressor region, and anode region. In some embodiments, substantially maintaining the pattern includes applying a mechanical force to at least one of the cathode region, gate region, suppressor region, and anode region to substantially maintain the pattern.
  • the apparatus is configured to vary as a function of time.
  • the gate electric potential (204) and/or the suppressor electric potential (210) may be substantially periodic, where the periodicity of the applied potential may be selected based on the travel time of the electrons between elements (102, 104, 106, 108).
  • the gate electric potential (204) and the suppressor electric potential (250) may be out of phase, where the phase difference may be determined at least partially by the travel time of the electrons between elements (102, 104, 106, 108).
  • the potential applied to this element may also be substantially periodic, and may be out of phase with the gate electric potential (204) and the suppressor electric potential (210).
  • the potentials are substantially periodic, they may be smoothly varying similar to a sine wave, they may be a series of pulses, or they may have a different configuration.
  • the gate electric potential (204), the suppressor electric potential (210), and/or any other potential applied to another element such as the screen grid (302) may include one or more pulses that may or may not be
  • timing of the pulses may be selected according to the travel time of the electrons between the elements (102, 104, 106, 108).
  • the cathode region includes an area at least partially defined by the cathode 102
  • the gate region includes an area at least partially defined by the gate 104
  • the suppressor region includes an area at least partially defined by the suppressor 106
  • the anode region includes an area at least partially defined by the anode 108.
  • a method corresponding to an apparatus including a cathode region, a gate region, a suppressor region, and an anode region comprises applying an anode electric potential to the anode region that is greater than a cathode electric potential of the cathode region, applying a gate electric potential to the gate region to release a set of electrons from the cathode region; passing the set of electrons from the gate region to the suppressor region; applying a suppressor electric potential to decelerate the set of electrons between the suppressor region and the anode region; binding the set of electrons in the anode region; and varying at, least one of the anode electric potential, gate electric potential, and suppressor electric potential as a function of time.
  • the variation of the potentials may occur in a variety of ways including but not limited to those previously described.
  • the method may further comprise receiving a signal and varying at least one of the anode electric potential (202), gate electric potential (204), and suppressor electric potential (210) responsive to the received signal.
  • the signal may correspond to a measured quantity of the apparatus, such as an anode current, a temperature of one or more of the elements (102, 104, 106, 108), a relati ve thermodynamic efficiency and/or relative power output of the apparatus, or another quantity related to the apparatus.
  • the pulse may be described by a function having a pulse width and center (e.g., gate pulse duration and center time, suppressor pulse duration and center time).
  • the center times of different pulses may be different, i.e. there may be a delay between, for example the gate pulse center time and the suppressor pulse center time.
  • the elements may have potentials that are pulsed, and the number and arrangement of elements and the pulses and their respective delays may be selected according to a particular embodiment, and may be determined at least in part by the travel time of the electrons emitted by the cathode. Further, optimum operating conditions may be selected by trial and error, may be selected via a computer program, or they may be determined by some combination of the two.
  • the pulse may be substantially a Gaussian distribution, it may be substantially square, or it may have another distribution. Where relevant, one of skill in the art may determine the center and width of the pulse and/or delays between pulses based on established methods.
  • an apparatus as described previously may further comprise circuitry operably connected to at least one of the first, second , and third power sources (110, 112, 114) to vary at least one of the anode electric potential (202), the gate electric potential (204), and/or the suppressor electric potential (210) as a function of time as described in the preceding paragraphs.
  • the circuitry may be receptive to signals (either user input, a signal including dimensions of the device, a signal with measured parameter of the device such as currents and/or temperatures, and/or another type of signal) to determine a relative thermodynamic efficiency, relative power density, or another quantity that is indicative of the operation of the apparatus.
  • the circuitry may be configured to select quantities such as the pulse duration, center time, and/or frequency based on calculated output values such as the relative thermodynamic efficiency and relative power density, and/or based on measured values such as current, temperature, or another measured parameter of the apparatus.
  • a method comprises receiving a first signal corresponding to a heat engine, the heat engine including an anode, cathode, spacer region, gate and suppressor, processing the first signal to determine an output parameter of the heat engine as a function of an anode electric potential applied to the anode, a gate electric potential applied to the gate, and a suppressor electric potential applied to the suppressor; producing a second signal corresponding to a selected value of the output parameter; and transmitting the second signal.
  • the output parameter may include a relative thermodynamic efficiency, a relative power output, or a different measure of the operation of the apparatus.
  • the potentials may be pulsed and/or substantially periodic, and parameters associated with these time varying potentials may be incorporated into calculations/processing.
  • Other embodiments may control the flow of electrons from the cathode 102 to the anode 108 such that the anode 108 provides alternating current (AC) to a load.
  • AC alternating current
  • the position of one or more of the cathode, gate, suppressor, and/or anode (102, 104, 106, 108) may vary as a function of time (for example, periodically) in order to produce a substantially AC output from the anode, as has been described previously herein.
  • varying the position of one or more of the elements (102, 104, 106, 1 08) may be achieved, for example, by operably connecting a voice coil or other acoustic driver to one or more of the elements (102, 104, 106, 108), where in these embodiments the output, frequency of the apparatus may be substantially in the audio frequency band.
  • At least one of the anode electric potential (202), the gate electric potential (204), and/or the suppressor electric potential (210) m ay be varied as a function of time to produce an AC output at the anode.
  • the time variation is substantially periodic the variation (such as a movement, of one or more of the elements (102, 104, 106, 108), a variation in the electric potential provided to the one or more elements (502, 104, 106, 108 ), or other factor causing an AC output as described herein) may be described as having a first frequency range and the AC output may be described as having a second frequency range, where in some embodiments the second frequency range may be substantially the same as the first frequency range.
  • an AC output at the anode may be achieved by varying the spatial position of one or more of the field emission enhancement features (103).
  • the field emission enhancement feature (103) may have a vibrational resonance that can be mechanically excited to temporally vary the distance from the field emission enhancement feature (103) to the gate (104). Such lateral vibrations may bring the tip of the field emission
  • the enhancement feature (103) nearer or further from the grid, varying the electric field felt by the tip of the field emission enhancement feature (103), and therefore varying the emission current from, the field emission enhancement feature ( 03).
  • This configuration naturally delivers variable-amplitude power at the vibrational frequency of the emitter.
  • the gate (104) forms an asymmetric pattern around the emitter (for example, a square hole in a metal grid)
  • the device may have multiple vibrational modes and the frequency range of the device may be greater than that of a device having, for example, a gate with a circular hole around the emitter.
  • the field emission enhancement, feature (103) includes a nanotube
  • the operational frequency range of the device may be substantially in the RF portion of the electromagnetic spectrum. In such an embodiment the nanotube may be selected to have GHz vibrational resonance frequencies.
  • oscillations (or vibrations, resonances, etc.) of one or more field emission enhancement feature(s) (103) may be produced by applying a surface acoustic wave to the cathode to acoustically oscillate the field emission enhancement feature(s) (103).
  • a surface acoustic wave to the cathode to acoustically oscillate the field emission enhancement feature(s) (103).
  • cathode vibration can produce net relative variation in the spacing between the field emission enhancement feature(s) (103) and the gate, and hence to the current from the anode.
  • circuitry for example, the circuitry 402 shown in Figure 4
  • control an apparatus such as those described herein.
  • two or more field emission devices are arranged in an array.
  • the apparatus 100 as shown in Figure 1 which operates as a heat engine, and/or its various permutations as described herein, may be configured such that two or more such devices form an array.
  • circuitry may be used to address individual devices in the array such that when an apparatus 100 in the array is addressed, electrons flow between the cathode and anode as previously described herein.
  • each field emission enhancement feature 103 in the array may be separately addressable.
  • each field emission enhancement feature 103 may be electrically and/or thermally isolated from the other field emission enhancement features 103 in the array such that it may operate substantially independently of the other field emission enhancement features 103 in the array.
  • selected groups of fieid emission enhancement features 103 may be separately addressable. For example, a group of nearest-neighbor field emission enhancement features 103 may be addressed together, which may allow for selection one or more portions of the array to be functioning at any given time.
  • Circuitry 402 may be arranged relative to the array to control the operation of individual field emission devices in the array. This circuitry 402 may include those functions described previously with respect to a single apparatus 100, and the circuitry may further be configured to control each apparatus 100 in the array.
  • the circuitry may include one or more feedback mechanisms, and may receive signals indicative of one or more currents, temperatures, frequencies, etc.
  • each field emission enhancement feature 103 in the array is thermally and electrically connected to the other field emission enhancement features 103 in the array, however, the gates 104 of each of the field emission devices are electrically isolated such that the gates 104 of each field emission device are each separately addressable.
  • Addressing may include, but is not limited to, varying the temperature of the cathode 102, varying the gate electric potential 204, varying the suppressor electric potential 210, varying the anode electric potential 202, varying a. frequency of an applied force, and/or varying some other parameter of the device as described herein.
  • sub-groups of field emission devices in an array of field emission devices may be electrically connected and/or configured so that they are controlled by a single circuit (i.e., that all of the field emission devices in the subgroup can be turned on, turned off, and/or otherwise adjusted together as a group). This may be done, for example, in order to limit damage to an array in the event of malfunction.
  • the device may be configured such that a detector (such as a device for measuring current at the gate 104) sends a signal to the circuitry 402 and the circuitry 402 further sends a signal to stop the operation of the other field emission devices in the sub-group of the damaged device.
  • emission from the cathode (102) may be enhanced electromagnetically as was shown and described with respect to FIG. 1 7.
  • the electromagnetic energy (the electromagnetic energy may also be described as an electromagnetic wave, photon(s), etc.) may be applied to the cathode (102) in the ways that were described with respect to FIG. 17, and/or may also be applied from behind the emitter tip (i.e., from the opposite side of the cathode 102 with respect to the anode 108).
  • eiectromagnetically enhanced emission from the cathode (102) may further be enhanced by the application of a surface plasmons at the cathode (102).
  • addressing of individual field emission devices in an array of field emission devices may be done according to an expected performance of the device(s). For example, in some embodiments one or more field emission devices in the array of field emission devices may have an optimal current range, and the number of devices in the array that are turned on at any given time may be adjusted such that the optimal current range for an individual device is not exceeded. Further, individual field emission devices may be cycled on and off in order to prolong their life, such that each individual device in the array is not in continuous operation while the array as a whole is in continuous operation.
  • the electrons passing close to the loop may experience a force in a direction pointing towards the center of the loop.
  • magnetic fields or other techniques in electron optics may be used to adjust the trajectories of the electrons.
  • the field emission device may be configured similarly to a. klystron, as shown in Figure 24, where the potentials on the gate 104 (and, in some embodiments, the suppressor 106 as well), are temporally varied in such a way as to "bunch" the electron beam in a similar way as a klystron.
  • the field emission device configured similarly to a klystron may further include an inductive coupler 2402.
  • the inductive coupler 2402 is an electromagnetic cavity resonator (such as a toroidal cavity resonator) that is configured such that when the bunched electrons pass through the resonator, electromagnetic energy is inductively coupled into the resonator.
  • Figure 24 shows the inductive coupler 2402 as being situated between the gate 104 and the suppressor 106
  • the inductive coupler may 2402 may have a different configuration relative to the elements 102, 104, 106, 108.
  • the configuration of klystrons and related devices are known to those of skill in the art, and embodiments incorporating elements from these configurations may be incorporated according to a particular embodiment.
  • the device may include one or more additional elements similar to the gate 104 and/or the suppressor 106 (where, for example, the additional element may be configured similarly to the control grid shown in Figure 23), where a potential applied to the additional element may be selected to further modulate (or "bunch") the electron beam.
  • At least one of the cathode 102 and the anode 108 is operably connected to circuitry to control an output of the anode 108.
  • the cathode 102 is operably connected to one or more circuit elements configured to provide the cathode with a substantially fixed current source, and may be configured so the current cannot increase beyond an upper limit.
  • the current-regulating circuit elements may include, for example, a field effect transistor (FET), a bipolar transistor, a resistor, or a different type of element.
  • FET field effect transistor
  • the current limiting element(s) may be configured to regulate the current to an individual field emission device or it may be configured relative to two or more field emission devices to regulate the current to more than one device simultaneously.
  • the circuitry configured to regulate the current to the cathode 102 is also configured to regulate the gate electric potential 204.
  • a field emission device may include a thermal reservoir configured to make a connection to the cathode to transfer heat to the cathode, and circuitry configured to control the connection.
  • the thermal reservoir may be configured to make mechanical contact (or near-contact, with evanescent wave transfer of energy), where the circuitry may be configured to adjust a position of the reservoir and/or of a switch to facilitate the mechanical contact (or near contact).
  • the circuitry is configured to modulate a potential difference between the cathode and the thermal reservoir to transfer energy between them.
  • a substantially AC (i.e., substantially periodically varying) output may be created by- combining two field emission devices with DC outputs to form an electrical inverter according to methods known to those of skill in the art of electronics.
  • power MOSFETs may be employed.
  • one or more field emission devices may be configured relative to one or more transformers, where the output of the field emission devices may be either DC or AC, depending on the particular configuration of the device as described previously herein.
  • the output of a pulsed or AC field emission device is operabiy connected to a high-current, low-voltage transformer. This transformer is operabiy connected to a lower-current higher- voltage winding. This is just one example of the many ways that a transformer may be configured relative to a field emission device.
  • circuitry may be configured relative to the device to control the phase of the output signal.
  • the field emission device may be configured relative to circuit elements and/or control circuitry (or simply, “circuitry”), and the foregoing present just a few examples of such configurations.
  • an implementer may opt for a mainly hardware and/or firmware vehicle; alternatively, if flexibility is paramount, the implementer may opt for a mainly software implementation; or, yet again alternatively, the implementer may opt for some combination of hardware, software, and'or firmware.
  • any vehicle to be utilized is a choice dependent upon the context in which the vehicle will be deployed and the specific concerns (e.g., speed, flexibility, or predictability) of the implementer, any of which may vary.
  • Those skilled in the art will recognize that optical aspects of impleme tations will typically employ optically-oriented hardware, software, and or firmware.
  • logic and similar implementations may include software or other control structures.
  • Electronic circuitry may have one or more paths of electrical current constructed and arranged to implement various functions as described herein.
  • one or more media may be configured to bear a device-detectable implementation when such media hold or transmit a device detectable instructions operable to perform as described herein.
  • implementations may include an update or modification of existing software or firmware, or of gate arrays or programmable hardware, such as by performing a reception of or a transmission of one or more instructions in relation to one or more operations described herein.
  • an implementation may include special-purpose hardware, software, firmware components, and/or general-purpose components executing or otherwise invoking special-purpose components.
  • Specifications or other implementations may be transmitted by one or more instances of tangible transmission media as described herein, optionally by packet transmission or otherwise by passing through distributed media at various times.
  • implementations may include executing a special-purpose instruction sequence or invoking circuitry for enabling, triggering, coordinating, requesting, or otherwise causing one or more occurrences of virtually any functional operations described herein.
  • operational or other logical descriptions herein may be expressed as source code and compiled or otherwise invoked as an executable instruction sequence.
  • implementations may be provided, in whole or in part, by source code, such as C++, or other code sequences.
  • source or other code implementation may be compiled/implemented''transIated/converted into a high-level descriptor language (e.g., initially implementing described technologies in C or C++ programming language and thereafter converting the programming language implementation into a logic-synthesizable language implementation, a hardware description language impleme tation, a hardware design simulation implementation, and/or other such similar mode(s) of expression).
  • a high-level descriptor language e.g., initially implementing described technologies in C or C++ programming language and thereafter converting the programming language implementation into a logic-synthesizable language implementation, a hardware description language impleme tation, a hardware design simulation implementation, and/or other such similar mode(s) of expression.
  • a logical expression e.g., computer programming language implementation
  • a Verilog-type hardware description e.g., via Hardware Description Language (HDL) and/or Very High Speed Integrated Circuit Hardware Descriptor Language (VHDL)
  • VHDL Very High Speed Integrated Circuit Hardware Descriptor Language
  • Those skilled in the art will recognize how to obtain, configure, and optimize suitable transmission or computational elements, material supplies, actuators, or other structures in light of these teachings.
  • Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog
  • a communication medium e.g., a fiber optic cable, a waveguide, a wired
  • a wireless communication link e.g., transmitter, receiver, transmission logic, reception logic, etc., etc.
  • electrical circuitry includes, but is not, limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least, one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memor device (e.g., forms of memory (e.g., random access, flash, read only, etc.)), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, optical - electrical equipment, etc.).
  • a memor device e.g., forms of memory (e.g., random access, flash, read only, etc.)
  • communications device e.g., a modem, communications switch, optical - electrical equipment,
  • a data processing system generally includes one or more of a system unit housing, a video display device, memory such as volatile or non-volatile memory, processors such as microprocessors or digital signal processors, computational entities such as operating systems, drivers, graphical user interfaces, and applications programs, one or more interaction devices (e.g., a touch pad, a touch screen, an antenna, etc.), and/or control systems including feedback loops and control motors (e.g., feedback for sensing position and/or velocity; control motors for moving and/or adjusting components and/or quantities).
  • a data processing system may be implemented utilizing suitable commercially available components, such as those typically found in data
  • examples of such other devices and/or processes and/or systems might include - as appropriate to context and application— all or part of devices and/or processes and/or systems of (a) an air conveyance (e.g., an airplane, rocket, helicopter, etc.) , (b) a ground conveyance (e.g., a car, truck, locomotive, tank, armored personnel carrier, etc.), (c) a building (e.g., a home, warehouse, office, etc.), (d) an appliance (e.g., a refrigerator, a washing machine, a dryer, etc.), (e) a communications system (e.g., a networked system, a telephone system, a Voice over IP system, etc.), (f) a business entity (e.g., an Internet Service Provider (ISP) entity such as Comcast Cable, Qwest, Southwestern Bell, etc.), or (g) a wired/wireless services entity (e.g.. Sprint, Cingular,
  • ISP Internet Service Provider
  • a sale of a system or method may likewise occur in a territory even if components of the system or method are located and/or used outside the territory.
  • implementation of at least part of a system for performing a method in one territory does not preclude use of the system in another territory.
  • any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components.
  • any two components so associated can also be viewed as being “operably connected”, or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable,” to each other to achieve the desired functionality.
  • operably couplable include but are not limited to physically mateable and/or physically interacting components, and/or wirelessly interactable, and/or wire!ess!y interacting components, and/or logically interacting, and/or logically interactable component .

Landscapes

  • Cold Cathode And The Manufacture (AREA)
  • Testing Or Measuring Of Semiconductors Or The Like (AREA)

Abstract

Dans un mode de réalisation, la trajectoire d'un ou de plusieurs électrons est régulée dans un dispositif à émission de champ. Dans un autre mode de réalisation, ledit dispositif à émission de champ est configuré de manière analogue à un klystron. Dans un autre mode de réalisation encore, ledit dispositif à émission de champ est conçu avec des circuits électriques sélectionnés de manière à assurer la commande de l'entrée et de la sortie du dispositif.
PCT/US2013/038476 2012-04-26 2013-04-26 Modes de réalisation d'un dispositif à émission de champ WO2013163589A2 (fr)

Applications Claiming Priority (18)

Application Number Priority Date Filing Date Title
US201261638986P 2012-04-26 2012-04-26
US61/638,986 2012-04-26
US13/545,504 US9018861B2 (en) 2011-12-29 2012-07-10 Performance optimization of a field emission device
US13/545,504 2012-07-10
US13/587,762 US8692226B2 (en) 2011-12-29 2012-08-16 Materials and configurations of a field emission device
US13/587,762 2012-08-16
US13/666,759 US8946992B2 (en) 2011-12-29 2012-11-01 Anode with suppressor grid
US13/666,759 2012-11-01
US13/774,893 US9171690B2 (en) 2011-12-29 2013-02-22 Variable field emission device
US13/774,893 2013-02-22
US13/790,613 2013-03-08
US13/790,613 US8970113B2 (en) 2011-12-29 2013-03-08 Time-varying field emission device
US13/860,274 US8810131B2 (en) 2011-12-29 2013-04-10 Field emission device with AC output
US13/860,274 2013-04-10
US13/864,957 2013-04-17
US13/864,957 US8810161B2 (en) 2011-12-29 2013-04-17 Addressable array of field emission devices
US13/871,673 US8928228B2 (en) 2011-12-29 2013-04-26 Embodiments of a field emission device
US13/871,673 2013-04-26

Publications (2)

Publication Number Publication Date
WO2013163589A2 true WO2013163589A2 (fr) 2013-10-31
WO2013163589A3 WO2013163589A3 (fr) 2015-06-18

Family

ID=49484040

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2013/038476 WO2013163589A2 (fr) 2012-04-26 2013-04-26 Modes de réalisation d'un dispositif à émission de champ

Country Status (1)

Country Link
WO (1) WO2013163589A2 (fr)

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE504158A (fr) * 1950-05-17
JP3235172B2 (ja) * 1991-05-13 2001-12-04 セイコーエプソン株式会社 電界電子放出装置
US5908699A (en) * 1996-10-11 1999-06-01 Skion Corporation Cold cathode electron emitter and display structure
GB2330687B (en) * 1997-10-22 1999-09-29 Printable Field Emitters Ltd Field emission devices
US6031336A (en) * 1998-06-17 2000-02-29 Motorola, Inc. Field emission display and method for the operation thereof
TWM309746U (en) * 2000-10-19 2007-04-11 Matsushita Electric Ind Co Ltd Driving apparatus for a field emission device, field emission device, electron source, light source, image display apparatus, electron gun, electron beam apparatus, cathode ray tube, and discharge tube
US6563185B2 (en) * 2001-05-21 2003-05-13 The Regents Of The University Of Colorado High speed electron tunneling device and applications
US20090011706A1 (en) * 2006-05-23 2009-01-08 Innovision Research & Technology Plc Near field RF communicators and near field communications-enabled devices
US8692226B2 (en) * 2011-12-29 2014-04-08 Elwha Llc Materials and configurations of a field emission device

Also Published As

Publication number Publication date
WO2013163589A3 (fr) 2015-06-18

Similar Documents

Publication Publication Date Title
US8928228B2 (en) Embodiments of a field emission device
US8810161B2 (en) Addressable array of field emission devices
US8969848B2 (en) Materials and configurations of a field emission device
US8810131B2 (en) Field emission device with AC output
US9824845B2 (en) Variable field emission device
EP2801102B1 (fr) Anode dotée d'une grille de suppresseur
US9349562B2 (en) Field emission device with AC output
US8946992B2 (en) Anode with suppressor grid
US8970113B2 (en) Time-varying field emission device
US8803435B2 (en) Field emission device
TWI594286B (zh) 太赫茲反射速調管及微米太赫茲反射速調管陣列
US9384933B2 (en) Performance optimization of a field emission device
US9627168B2 (en) Field emission device with nanotube or nanowire grid
EP3007199A1 (fr) Dispositif de tube à électrons
WO2013163589A2 (fr) Modes de réalisation d'un dispositif à émission de champ
WO2013163450A2 (fr) Dispositif à émission de champ variant dans le temps
WO2013163452A2 (fr) Dispositif à émission de champ à sortie de courant alternatif
WO2013163439A1 (fr) Dispositif à émission de champ variable
CN107462545A (zh) 一种基于太赫兹波的检测系统
Murphy et al. Cold cathode microwave devices

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 13781331

Country of ref document: EP

Kind code of ref document: A2

NENP Non-entry into the national phase in:

Ref country code: DE

122 Ep: pct app. not ent. europ. phase

Ref document number: 13781331

Country of ref document: EP

Kind code of ref document: A2