CA1191283A - Intense transient magnetic field generation by laser- plasma - Google Patents
Intense transient magnetic field generation by laser- plasmaInfo
- Publication number
- CA1191283A CA1191283A CA000408648A CA408648A CA1191283A CA 1191283 A CA1191283 A CA 1191283A CA 000408648 A CA000408648 A CA 000408648A CA 408648 A CA408648 A CA 408648A CA 1191283 A CA1191283 A CA 1191283A
- Authority
- CA
- Canada
- Prior art keywords
- laser
- return current
- current path
- plasma
- magnetic field
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21B—FUSION REACTORS
- G21B1/00—Thermonuclear fusion reactors
- G21B1/11—Details
- G21B1/23—Optical systems, e.g. for irradiating targets, for heating plasma or for plasma diagnostics
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/06—Electromagnets; Actuators including electromagnets
- H01F7/20—Electromagnets; Actuators including electromagnets without armatures
- H01F7/202—Electromagnets for high magnetic field strength
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/10—Nuclear fusion reactors
Abstract
INTENSE TRANSIENT MAGNETIC FIELD GENERATION
BY LASER-PLASMA
Abstract of the Disclosure In a laser system, the return current of a laser gen-erated plasma is conducted near a target to subject that target to the magnetic field thereof. In alternate embod-iments the target may be either a small non-fusion object for testing under the magnetic field or a laser-fusion pellet. In the laser-fusion embodiment, the laser-fusion pellet is irradiated during the return current flow and the intense transient magnetic field is used to control the hot electrons thereof to hinder them from striking and heating the core of the irradiated laser-fusion pellet.
BY LASER-PLASMA
Abstract of the Disclosure In a laser system, the return current of a laser gen-erated plasma is conducted near a target to subject that target to the magnetic field thereof. In alternate embod-iments the target may be either a small non-fusion object for testing under the magnetic field or a laser-fusion pellet. In the laser-fusion embodiment, the laser-fusion pellet is irradiated during the return current flow and the intense transient magnetic field is used to control the hot electrons thereof to hinder them from striking and heating the core of the irradiated laser-fusion pellet.
Description
i~'I`F.~SE TE~ IE~T `1}~GNETlC ~'TEI.,D
G `r~ERA'I'IO~1 BY ri~ SEP~-PI ~.C'~.A
. _ , ,, .. .. , . .. .. _ The p.r:esent in~ention rela~'es ~en!-rally to gene.-r~tion of intense transienL mayne~ic fields and n-,ore particularly .o the generation of an intense transient m2anetic field through a laser-plasma method and app3r~tus.
One field in wh.ich such a generation of an intense transient Inagnetic fiela ~o~ld be rc)st us~ l is t.he field of laser-initiated thermonuclear rusion power generation.
One techniq~e proposed to generate electrical po~er from a controlled thermonuclear event involves injecting a small deuterium-tritium pellet into a vacuum chamber and trig-gerilly a fusion reaction by ~Idriving~ t:he deuterium and trit;~m ions toyether with the energy supplied by las,er beams to produce a heliuM ion and a neutron. Since the heliurn ion and neutron have slightly less mass than the deuterium and tritium ions a small amount of mass is con-verted into energy in accordance with the fanl.ous Einstein eq~ation E = mc2 where E equals the energy ~rod-~ced, m equals the nnass converted, and c equals the speed of light.
Absorption of the laser pulse q~1ickly hea.s the outer region of .he pellet co form an ioni.~ed ~35 or plasma that expands outward (blows off) rapidly. rrhe recorl impulse from the very rapid bl.owing off of the o~ter pellet layer compresses the pellet core in the same way .hat the impulse from a roc~et's exhaust p~shes the rocket forward, or a rifle shot recoil pushes the rifle ag~ir.st one's shoulaer.
'~' Theory predicts that the center of the pellet core will be compressed to superdensities; one to ten thousand times the normal solid densi~y, or about ten times the density of the center of the sun (about one hundred times as dense as lead~. Such pellet core densities are impor-tant beca~se they greatly increase the li~elihoOd that energetic deuterium and tritium ions will collide with one another. Also~ they enable still unfused d~uterium and tritium ions to recapture, or share, some of the energy of ~ fusion product helium particle before the high-velocity helium particle can escape ~he core region. This is anal-ogous to one fast moving billard ball striking and giving energy of motion to others. This energy sharing with unburned fuel gives rise to so-called ~'bootstrap" heating that further increases the reaction rate. Achievement of core compression is crucial to the laser fusion process.
In practice there are forces which oppose or hinder core compression. One problem just recently being recog-nized and studied is the effect of energetic or hot elec-trons generated in the pellet surface area plasma. Thehot electrons produced move rapidly around and penetrate the pellet core causing heating thereof which makes core compression more difficult and thus for a given laser energy less compression results and final energy gain is ~5 reduced. The problems caused by hot electrons and the need to control same are discussed by ~. B. Spielman et al., Physical Review Letters, Vol. ~fi, No. 13, p. 821 (30 March 1981). The measurement of a large return cur-rent in a laser-produced positively charged plasma is detailed by R. F~ Benjamin et al., Physical Review Letters, Vol. 42~ No. 14, p. 890 (2 April 1979).
It is therefore an object of the present invention to control the hot electrons of a laser produced plasma to reduce pellet core penetration thereby.
!
It is another object of the present invention to con-trol the hot electrons OI a laser produced plasma by the generation of an intense transient magnetic field.
It is still another object of ~he present invention to generate an intense transient magnetic field useful in controlling the hot electrons of a laser produced plasma and further useful in other areas such as in experimental research concerned with the response of biological cells, organisms and other items to magnetic stimuli.
In accordance with the present invention a first laser produced plasma is initiated purposely to generate hot electrons and a positively charged plasma which is pro-vided a low impedance path to ground to create an intense but very transient magnetic field via the high return cur-rent mechanism of the positively charged plasma. In one embodiment of the invention an object such as a biological cell or the like is confined within or near the provided low impedance path and is therefore subjected to the intense transient magnetic field. In another embodiment of the invention a fusion pellet is confined within or near the provided low impedance path and is laser irradi-ated shortly after the first laser produced plasma is ini-tiated and during the period of the intense magnetic field whereby the hot electrons of the fusion pellet plasma are confined to extremely tight orbits and are controlled and hindered from penetrating the core region of the fusion pellet.
~ n advantage of the present invention is that hot electrons of laser produced plasma are controlled by an earlier laser produced event thus the laser equipment needed and Eunctioning to produce the usion plasma can also be employed to produce the earlier hot electron con-trolling event.
Another a~vantage of the present invention is that an extremely intense and transient magnetic field i5 produced for organic and inorganic experimental purposes~
3~
Broadly, these objec-ts and advantages are at~ained by the invention which provides for an intense transient magnetic field producing apparatus for use with a high powered laser that com-prises emitter means for emitting hot electrons and creating a positively charged plasma when irradiated by the high powered laser, a target means for subjection to an intense transient magnetic fieldr and a grounding means connected to the emitter means and positioned near the target means. The grounding means provides a return current path to ground for the positively charged plasma created by the emitter means whereby an intense transient magnetic field is created near the target means when the emitter means is irradiated by the high powered laser.
In a more specific manner, that inventive apparatus includes a laser fusion system for the laser and the target means is a laser-fusion pellet.
The invention also contemplates a method of subjecting a plasma to an intense transient magne-tic field which comprises khe step~ of providing a re-turn current pat.h, yene.r.at:i.ng an lntense transient return current ~low ~lpon the r~tu:~n curr~nt path, and creating a plasma near the return current path durlny the intense transient return current flow thereupon whereby the plasma is subjected to the magnetic field thereof.
In a urther embodiment, the invention contemplates a method of subjecting an object to an intense -transient magnetic field in a laser system which comprises the steps of providi.ng a grounded return current path having an ungrounded end, securlng an emltter on the ungrounded end of the grounded return current path with the emltter fashloned so as to create a highly charged plasma when irradiated by a laser, placing the object near to the groundecl return current path, and laser irradiati.ny the emitter, the.reby creating the hlghly charyed plasma and causlny an intense transient return current flow on the grounded return current path whereby the object is subjected to -the magne-tic Eleld thereof.
In the latter inventive method, the system can be a laser-fuslon system, the object can be a laser-fuslon pelle-t that is fashloned so as to create a plasma when lrradiated by a laser, and the laser-fusion pellet is laser-irradiated during the intense transient return current flow on the grounded return current pa-th, thereby subjecting the plasma of the laser-fusion pellet to -the magnetic field of the intense transien-t return current flow.
-Additional objects, advantages and novel features ofthe invention will be set foxth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination oF the following or may be learned by practice of the invention. The ob~ects and advantages of the invention may be realized and attained by means of the instrumentalities and combina-tions particularly pointed out in the appended claims.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate an embod-iment of the present invention and, together with the des-crip~ion, serve to explain ~he principles of the inven-tion. In the drawings:
Figure 1 i,llustrates a target surrounded by a coil 1~ attached to an emitter at one end and grounded at the ; other:
Figure 2 illustrates a target surrounded by a cylln~
drical cage attached to an emitter at one end and grounded at the other; and Figure 3 details a configuration which surrounds a target with a coil in accord with embodiment of the inven-tion shown in Fig. 1.
In accord with the present invention, a target 11 is ', secured within an intense transient magnetic field produc-ing target assembly 13 connected to ground 15 at one end '` and to an emitter 17 at the other, see Fig. 1. When placed wi~hin an evacuated cavity and irradiated by an intense laser beam pulse, the emitter 17 ls transformed ,~ into a highly charged positive plasma causing an intense return current to flow between the ground 15 and the emitter 17 through the ~arget assembly 13 thereby subject-ing the target 11 to an intense txansient magnetic field.
The target assembly 13 formed as a helix or coil as shown in Fig. 1 subjects the target 11 to longitudinal magnetic field. Alternatively, the target assembly 13 may ~ !~
, .
.
:
be formed as a cage to subject the targe~ 11 to an a~i-muthal magnetic field, see Fig. 2~ It is of importance to keep the target assembly 13 of low inductance and low resistance in order to generate the desired intense tran-sient magnetic field.
The emitter 17 is preferably a microballoon of glass, plastic, metal, or any combination thereofO The emitter 17 is utilized to crea~e a positive plasma when irradiated by a laser beam pulse of about lol5 watts/cm2 or greater. With the hot electrons driven from the emitter 17 by the laser pulse, the high positive potential remain-ing causes an intense but transient current to flow through the target assembly 13 to ground 15, see Figs. 1 and 2. ~ suitable emitter is a glass microballoon of approximately 500 micrometers diameter~
Studies such as detailed ~y R. F. ~enjamin et al~, Physical Review Letters, Vol. 42, No. 14, p. 890 (2 April 1979) demonstrate that irradiated emitters can yenerate plasma potentials in the order of 180 kilovolts lasting for periods in the order of a nanosecond or more. Under such conditions intense transient magnetic fields on the order of a 100 or more kiloguass can be generated depend-ing upon the resistance and reactance of the return cur-rent path.
The target 11 is a small object on the order of 1 millimeter diameter. The target 11 may be organic, inorganic, metallic, non-metallic, or otherwise. In one application of the invention, the target 11 is a usion-fuel containing pellet. These pellets are usually sub-millimeter-diameter hollow spheres of glass or metal (called microballoons) filled with a high-pressure DT gas ; and frequently coated with additional layers, or sur-rounded by concentric shells of metal and/or plastic to optimize the interaction of the target 11 with a laser beam~
.~
.. ... .... ..
When the present invention is used in laser fusion experiments or power generation, a short duration o about or less than a nanosecond before a main laser beam strikes the ~arget 11, an auxiliary laser beam impinges on the - 5 emitter 17. The above described resultant "return cur-__ rent" crea~es a strong magnetic ~ield near the target 11 at the instant the target 11 is irradicated. The strong magnetic ield traps the hot electrons from the target 11 and keeps them in small orbits preventing them from heat-ing the fuel within the target 11 and causing their energyto be deposited in the region exterior to the fuel con-taining core.
The target assembly 13 may be sized and located as desired. For example, the target assembly 13 may be exterior to the absorption region (i.e., the volume sur-rounding the target 11 where the main laser beam irradia-tion is absorbed). With the target assembly 13 fashioned as a cylindrical cage (see Fig. 2) the Pree elec~rons from the target 11 are trapped in small orbits as above des-cribed. Alternatively, the target assembly 13 may be located between the laser absorption region and the target ` 11 to magnetically shield t~e fuel of the target 11 from ; hot (or "energetic") electrons. Other options exist such as fashioning the target assembly 13 as a coil or helix to create a longitudinal magnetic field, see Fig. 1.
The actual physical fabrication of the subject inven-tion is readily accomplished by those skilled in the art, see Fig~ 3. A round glass rod 19 preferrably about 4 cm ' in length and 2 mm in diameter is pulled to a tip 21 which `~ 30 is ground to 125 m diameter. The thick end 23 of the rod 19 is glued or otherwise secured to a metal base 25 while the tip 21 is likewise glued to the target 11 which may be a 1 mm aluminum ball or like sized DT fuel pellet The target assembly 13 being a 255 m diameter copper wire is soldered to the metal base 25 and coiled around the target .
:., 11. The emitter 17 being preferrably a 500 m glass microballoon is then glued to the target end 27 of the target assembly 13. To provide proper operation, the metal base 25 is connected ~o ground 15.
The present invention requires a ~ligh power laser facility. Such facilities are available at the Los Alamos National Laboratory and at numerous other laboratories, institutions and universities. An intense laser beam of about or greater than lol5 watts/cm2 irradiance is preferrable to generate the electromagnetic field neces-sary to accelerate electrons ~o velocities that enable them to escape the plasma and thereby create a positive potential at the plasma~ A carbon-dioxide laser is pre-ferred because it generates energetic electrons more effi-ciently than other commonly available lasers.
The foregoing description of a preferred embodiment ofthe invention has been presented for purposes oE illustra~
tion and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possi-ble in light of the above teaching. The embodiment was chosen and described in order to best explain the princi-ples of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contem plated. It is intended that the scope of the invention be defined by the c1aims appended hereto.
.
G `r~ERA'I'IO~1 BY ri~ SEP~-PI ~.C'~.A
. _ , ,, .. .. , . .. .. _ The p.r:esent in~ention rela~'es ~en!-rally to gene.-r~tion of intense transienL mayne~ic fields and n-,ore particularly .o the generation of an intense transient m2anetic field through a laser-plasma method and app3r~tus.
One field in wh.ich such a generation of an intense transient Inagnetic fiela ~o~ld be rc)st us~ l is t.he field of laser-initiated thermonuclear rusion power generation.
One techniq~e proposed to generate electrical po~er from a controlled thermonuclear event involves injecting a small deuterium-tritium pellet into a vacuum chamber and trig-gerilly a fusion reaction by ~Idriving~ t:he deuterium and trit;~m ions toyether with the energy supplied by las,er beams to produce a heliuM ion and a neutron. Since the heliurn ion and neutron have slightly less mass than the deuterium and tritium ions a small amount of mass is con-verted into energy in accordance with the fanl.ous Einstein eq~ation E = mc2 where E equals the energy ~rod-~ced, m equals the nnass converted, and c equals the speed of light.
Absorption of the laser pulse q~1ickly hea.s the outer region of .he pellet co form an ioni.~ed ~35 or plasma that expands outward (blows off) rapidly. rrhe recorl impulse from the very rapid bl.owing off of the o~ter pellet layer compresses the pellet core in the same way .hat the impulse from a roc~et's exhaust p~shes the rocket forward, or a rifle shot recoil pushes the rifle ag~ir.st one's shoulaer.
'~' Theory predicts that the center of the pellet core will be compressed to superdensities; one to ten thousand times the normal solid densi~y, or about ten times the density of the center of the sun (about one hundred times as dense as lead~. Such pellet core densities are impor-tant beca~se they greatly increase the li~elihoOd that energetic deuterium and tritium ions will collide with one another. Also~ they enable still unfused d~uterium and tritium ions to recapture, or share, some of the energy of ~ fusion product helium particle before the high-velocity helium particle can escape ~he core region. This is anal-ogous to one fast moving billard ball striking and giving energy of motion to others. This energy sharing with unburned fuel gives rise to so-called ~'bootstrap" heating that further increases the reaction rate. Achievement of core compression is crucial to the laser fusion process.
In practice there are forces which oppose or hinder core compression. One problem just recently being recog-nized and studied is the effect of energetic or hot elec-trons generated in the pellet surface area plasma. Thehot electrons produced move rapidly around and penetrate the pellet core causing heating thereof which makes core compression more difficult and thus for a given laser energy less compression results and final energy gain is ~5 reduced. The problems caused by hot electrons and the need to control same are discussed by ~. B. Spielman et al., Physical Review Letters, Vol. ~fi, No. 13, p. 821 (30 March 1981). The measurement of a large return cur-rent in a laser-produced positively charged plasma is detailed by R. F~ Benjamin et al., Physical Review Letters, Vol. 42~ No. 14, p. 890 (2 April 1979).
It is therefore an object of the present invention to control the hot electrons of a laser produced plasma to reduce pellet core penetration thereby.
!
It is another object of the present invention to con-trol the hot electrons OI a laser produced plasma by the generation of an intense transient magnetic field.
It is still another object of ~he present invention to generate an intense transient magnetic field useful in controlling the hot electrons of a laser produced plasma and further useful in other areas such as in experimental research concerned with the response of biological cells, organisms and other items to magnetic stimuli.
In accordance with the present invention a first laser produced plasma is initiated purposely to generate hot electrons and a positively charged plasma which is pro-vided a low impedance path to ground to create an intense but very transient magnetic field via the high return cur-rent mechanism of the positively charged plasma. In one embodiment of the invention an object such as a biological cell or the like is confined within or near the provided low impedance path and is therefore subjected to the intense transient magnetic field. In another embodiment of the invention a fusion pellet is confined within or near the provided low impedance path and is laser irradi-ated shortly after the first laser produced plasma is ini-tiated and during the period of the intense magnetic field whereby the hot electrons of the fusion pellet plasma are confined to extremely tight orbits and are controlled and hindered from penetrating the core region of the fusion pellet.
~ n advantage of the present invention is that hot electrons of laser produced plasma are controlled by an earlier laser produced event thus the laser equipment needed and Eunctioning to produce the usion plasma can also be employed to produce the earlier hot electron con-trolling event.
Another a~vantage of the present invention is that an extremely intense and transient magnetic field i5 produced for organic and inorganic experimental purposes~
3~
Broadly, these objec-ts and advantages are at~ained by the invention which provides for an intense transient magnetic field producing apparatus for use with a high powered laser that com-prises emitter means for emitting hot electrons and creating a positively charged plasma when irradiated by the high powered laser, a target means for subjection to an intense transient magnetic fieldr and a grounding means connected to the emitter means and positioned near the target means. The grounding means provides a return current path to ground for the positively charged plasma created by the emitter means whereby an intense transient magnetic field is created near the target means when the emitter means is irradiated by the high powered laser.
In a more specific manner, that inventive apparatus includes a laser fusion system for the laser and the target means is a laser-fusion pellet.
The invention also contemplates a method of subjecting a plasma to an intense transient magne-tic field which comprises khe step~ of providing a re-turn current pat.h, yene.r.at:i.ng an lntense transient return current ~low ~lpon the r~tu:~n curr~nt path, and creating a plasma near the return current path durlny the intense transient return current flow thereupon whereby the plasma is subjected to the magnetic field thereof.
In a urther embodiment, the invention contemplates a method of subjecting an object to an intense -transient magnetic field in a laser system which comprises the steps of providi.ng a grounded return current path having an ungrounded end, securlng an emltter on the ungrounded end of the grounded return current path with the emltter fashloned so as to create a highly charged plasma when irradiated by a laser, placing the object near to the groundecl return current path, and laser irradiati.ny the emitter, the.reby creating the hlghly charyed plasma and causlny an intense transient return current flow on the grounded return current path whereby the object is subjected to -the magne-tic Eleld thereof.
In the latter inventive method, the system can be a laser-fuslon system, the object can be a laser-fuslon pelle-t that is fashloned so as to create a plasma when lrradiated by a laser, and the laser-fusion pellet is laser-irradiated during the intense transient return current flow on the grounded return current pa-th, thereby subjecting the plasma of the laser-fusion pellet to -the magnetic field of the intense transien-t return current flow.
-Additional objects, advantages and novel features ofthe invention will be set foxth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination oF the following or may be learned by practice of the invention. The ob~ects and advantages of the invention may be realized and attained by means of the instrumentalities and combina-tions particularly pointed out in the appended claims.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate an embod-iment of the present invention and, together with the des-crip~ion, serve to explain ~he principles of the inven-tion. In the drawings:
Figure 1 i,llustrates a target surrounded by a coil 1~ attached to an emitter at one end and grounded at the ; other:
Figure 2 illustrates a target surrounded by a cylln~
drical cage attached to an emitter at one end and grounded at the other; and Figure 3 details a configuration which surrounds a target with a coil in accord with embodiment of the inven-tion shown in Fig. 1.
In accord with the present invention, a target 11 is ', secured within an intense transient magnetic field produc-ing target assembly 13 connected to ground 15 at one end '` and to an emitter 17 at the other, see Fig. 1. When placed wi~hin an evacuated cavity and irradiated by an intense laser beam pulse, the emitter 17 ls transformed ,~ into a highly charged positive plasma causing an intense return current to flow between the ground 15 and the emitter 17 through the ~arget assembly 13 thereby subject-ing the target 11 to an intense txansient magnetic field.
The target assembly 13 formed as a helix or coil as shown in Fig. 1 subjects the target 11 to longitudinal magnetic field. Alternatively, the target assembly 13 may ~ !~
, .
.
:
be formed as a cage to subject the targe~ 11 to an a~i-muthal magnetic field, see Fig. 2~ It is of importance to keep the target assembly 13 of low inductance and low resistance in order to generate the desired intense tran-sient magnetic field.
The emitter 17 is preferably a microballoon of glass, plastic, metal, or any combination thereofO The emitter 17 is utilized to crea~e a positive plasma when irradiated by a laser beam pulse of about lol5 watts/cm2 or greater. With the hot electrons driven from the emitter 17 by the laser pulse, the high positive potential remain-ing causes an intense but transient current to flow through the target assembly 13 to ground 15, see Figs. 1 and 2. ~ suitable emitter is a glass microballoon of approximately 500 micrometers diameter~
Studies such as detailed ~y R. F. ~enjamin et al~, Physical Review Letters, Vol. 42, No. 14, p. 890 (2 April 1979) demonstrate that irradiated emitters can yenerate plasma potentials in the order of 180 kilovolts lasting for periods in the order of a nanosecond or more. Under such conditions intense transient magnetic fields on the order of a 100 or more kiloguass can be generated depend-ing upon the resistance and reactance of the return cur-rent path.
The target 11 is a small object on the order of 1 millimeter diameter. The target 11 may be organic, inorganic, metallic, non-metallic, or otherwise. In one application of the invention, the target 11 is a usion-fuel containing pellet. These pellets are usually sub-millimeter-diameter hollow spheres of glass or metal (called microballoons) filled with a high-pressure DT gas ; and frequently coated with additional layers, or sur-rounded by concentric shells of metal and/or plastic to optimize the interaction of the target 11 with a laser beam~
.~
.. ... .... ..
When the present invention is used in laser fusion experiments or power generation, a short duration o about or less than a nanosecond before a main laser beam strikes the ~arget 11, an auxiliary laser beam impinges on the - 5 emitter 17. The above described resultant "return cur-__ rent" crea~es a strong magnetic ~ield near the target 11 at the instant the target 11 is irradicated. The strong magnetic ield traps the hot electrons from the target 11 and keeps them in small orbits preventing them from heat-ing the fuel within the target 11 and causing their energyto be deposited in the region exterior to the fuel con-taining core.
The target assembly 13 may be sized and located as desired. For example, the target assembly 13 may be exterior to the absorption region (i.e., the volume sur-rounding the target 11 where the main laser beam irradia-tion is absorbed). With the target assembly 13 fashioned as a cylindrical cage (see Fig. 2) the Pree elec~rons from the target 11 are trapped in small orbits as above des-cribed. Alternatively, the target assembly 13 may be located between the laser absorption region and the target ` 11 to magnetically shield t~e fuel of the target 11 from ; hot (or "energetic") electrons. Other options exist such as fashioning the target assembly 13 as a coil or helix to create a longitudinal magnetic field, see Fig. 1.
The actual physical fabrication of the subject inven-tion is readily accomplished by those skilled in the art, see Fig~ 3. A round glass rod 19 preferrably about 4 cm ' in length and 2 mm in diameter is pulled to a tip 21 which `~ 30 is ground to 125 m diameter. The thick end 23 of the rod 19 is glued or otherwise secured to a metal base 25 while the tip 21 is likewise glued to the target 11 which may be a 1 mm aluminum ball or like sized DT fuel pellet The target assembly 13 being a 255 m diameter copper wire is soldered to the metal base 25 and coiled around the target .
:., 11. The emitter 17 being preferrably a 500 m glass microballoon is then glued to the target end 27 of the target assembly 13. To provide proper operation, the metal base 25 is connected ~o ground 15.
The present invention requires a ~ligh power laser facility. Such facilities are available at the Los Alamos National Laboratory and at numerous other laboratories, institutions and universities. An intense laser beam of about or greater than lol5 watts/cm2 irradiance is preferrable to generate the electromagnetic field neces-sary to accelerate electrons ~o velocities that enable them to escape the plasma and thereby create a positive potential at the plasma~ A carbon-dioxide laser is pre-ferred because it generates energetic electrons more effi-ciently than other commonly available lasers.
The foregoing description of a preferred embodiment ofthe invention has been presented for purposes oE illustra~
tion and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possi-ble in light of the above teaching. The embodiment was chosen and described in order to best explain the princi-ples of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contem plated. It is intended that the scope of the invention be defined by the c1aims appended hereto.
.
Claims (23)
1. An intense transient magnetic field producing appara-tus for use with a high powered laser, said apparatus comprising:
emitter means for emitting hot electrons and creating a positively charged plasma when irradiated by the high powered laser;
target means for subjection to an intense tran-sient magnetic field; and grounding means connected to said emitter means and positioned near said target means, said grounding means for providing a return current path to ground for said positively charged plasma created by said emitter means whereby an intense transient magnetic field is created near said target means when said emitter means is irradiated by the high powered laser.
emitter means for emitting hot electrons and creating a positively charged plasma when irradiated by the high powered laser;
target means for subjection to an intense tran-sient magnetic field; and grounding means connected to said emitter means and positioned near said target means, said grounding means for providing a return current path to ground for said positively charged plasma created by said emitter means whereby an intense transient magnetic field is created near said target means when said emitter means is irradiated by the high powered laser.
2. The apparatus according to claim 1 wherein said return current path provided by said grounding means includes a portion fashioned as a coil around said target means.
3. The apparatus according to claim 1 where said return current path provided by said grounding means includes a portion fashioned as a cylindrical cage around said target means.
4. The apparatus according to claim 1 wherein said emitter means is a microballoon.
5. The apparatus according to claim 4 wherein said micro-balloon is a glass microballoon.
6. An intense transient magnetic field producing appara-tus for use with a laser fusion system having a high powered laser, said apparatus comprising:
emitter means for emitting hot electrons and creating a positively charged plasma when irradiated by the high powered laser;
a laser-fusion pellet for subjection to an intense transient magnetic field; and grounding means connected to said emitter means and positioned near said laser-fusion pellet, said grounding means for providing a return current path to ground for said positively charged plasma created by said emitter means whereby an intense transient mag-netic field is created near said laser-fusion pellet when said emitter means is irradiated by the high powered laser.
emitter means for emitting hot electrons and creating a positively charged plasma when irradiated by the high powered laser;
a laser-fusion pellet for subjection to an intense transient magnetic field; and grounding means connected to said emitter means and positioned near said laser-fusion pellet, said grounding means for providing a return current path to ground for said positively charged plasma created by said emitter means whereby an intense transient mag-netic field is created near said laser-fusion pellet when said emitter means is irradiated by the high powered laser.
7. The apparatus according to claim 6 wherein said return current path provided by said grounding means includes a portion fashioned as a coil around said laser-fusion pellet.
8. The apparatus according to claim 6 where said return current path provided by said grounding means includes a portion fashioned as a cylindrical cage around said laser-fusion pellet.
9. The apparatus according to claim 6 wherein said emitter means is a microballoon.
10. The apparatus according to claim 9 wherein said micro-balloon is a glass microballoon.
11. The apparatus according to claim 7 wherein said laser-fusion pellet has a defined absorption region external to said laser-fusion pellet and said portion of said ground-ing means fashioned as a coil surrounds said laser-fusion pellet within said defined absorption region.
12. The apparatus according to claim 7 wherein said laser-fusion pellet has a defined absorption region external to said laser-fusion pellet and said portion of said ground-ing means fashioned as a coil surrounds said defined absorption region.
13. The apparatus according to claim 8 wherein said laser-fusion pellet has a defined absorption region external to said laser-fusion pellet and said portion of said ground-ing means fashioned as a cylindrical cage surrounds said laser-fusion pellet within said defined absorption region.
14. The apparatus according to claim 8 wherein said laser-fusion pellet has a defined absorption region external to said laser-fusion pellet and said portion of said ground-ing means fashioned as a cylindrical cage surrounds said defined absorption region.
15. A method of subjecting a plasma to an intense tran-sient magnetic field comprising the steps of:
providing a return current path;
generating an intense transient return current flow upon said return current path; and creating a plasma near said return current path during said intense transient return current flow there upon whereby said plasma is subjected to the magnetic field thereof.
providing a return current path;
generating an intense transient return current flow upon said return current path; and creating a plasma near said return current path during said intense transient return current flow there upon whereby said plasma is subjected to the magnetic field thereof.
16. The method of claim 15 wherein said return current path includes a portion fashioned as a coil and said plasma is created therein.
17. The method of claim 15 wherein said return current path includes a portion fashioned as a cylindrical cage and said plasma is created therein.
18. In a laser system, a method of subjecting an object to an intense transient magnetic field, said method compris-ing the steps of:
providing a grounded return current path having an ungrounded end;
securing an emitter on said ungrounded end of said grounded return current path, said emitter fashioned so as to create a highly charged plasma when irradiated by a laser;
placing said object near to said grounded return current path; and laser irradiating said emitter thereby creating said highly charged plasma and causing an intense transient return current flow on said grounded return current path whereby said object is subjected to the magnetic field thereof.
providing a grounded return current path having an ungrounded end;
securing an emitter on said ungrounded end of said grounded return current path, said emitter fashioned so as to create a highly charged plasma when irradiated by a laser;
placing said object near to said grounded return current path; and laser irradiating said emitter thereby creating said highly charged plasma and causing an intense transient return current flow on said grounded return current path whereby said object is subjected to the magnetic field thereof.
19. The method of claim 18 wherein said grounded return current path includes a portion fashioned as a coil and said object is placed therein.
20. The method of claim 18 wherein said grounded return current path includes a portion fashioned as a cylindrical cage and said object is placed therein.
21. In a laser-fusion system, a method of subjecting the plasma of a laser irradiated laser-fusion pellet to an intense transient magnetic field, said method comprising the steps of:
providing a grounded return current path having an ungrounded end;
securing an emitter on said ungrounded end of said grounded return current path, said emitter fashioned so as to create a highly charged plasma when irradiated by a laser;
placing a laser-fusion pellet near to said grounded return current path, said laser-fusion pellet fashioned so as to create a plasma when irradiated by a laser;
laser irradiating said emitter thereby creating said highly charged plasma and causing an intense transient return current flow on said grounded return current path; and laser irradiating said laser-fusion pellet during said intense transient return current flow on said grounded return current path thereby subjected said plasma of said laser-fusion pellet to the magnetic field of said intense transient return current flow.
providing a grounded return current path having an ungrounded end;
securing an emitter on said ungrounded end of said grounded return current path, said emitter fashioned so as to create a highly charged plasma when irradiated by a laser;
placing a laser-fusion pellet near to said grounded return current path, said laser-fusion pellet fashioned so as to create a plasma when irradiated by a laser;
laser irradiating said emitter thereby creating said highly charged plasma and causing an intense transient return current flow on said grounded return current path; and laser irradiating said laser-fusion pellet during said intense transient return current flow on said grounded return current path thereby subjected said plasma of said laser-fusion pellet to the magnetic field of said intense transient return current flow.
22. The method of claim 21 wherein said grounded return current path includes a portion fashioned as a coil and said laser-fusion pellet is placed therein.
23. The method of claim 21 wherein said grounded return current path includes a portion fashioned as a cylindrical cage and said laser-fusion pellet is placed therein.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29391081A | 1981-08-18 | 1981-08-18 | |
| US293,910 | 1981-08-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1191283A true CA1191283A (en) | 1985-07-30 |
Family
ID=23131084
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408648A Expired CA1191283A (en) | 1981-08-18 | 1982-08-03 | Intense transient magnetic field generation by laser- plasma |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5839986A (en) |
| CA (1) | CA1191283A (en) |
| DE (1) | DE3230712A1 (en) |
| FR (1) | FR2515470B1 (en) |
| GB (1) | GB2104296B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5796156A (en) * | 1980-12-01 | 1982-06-15 | Sekisui House Kk | Mount construction of building panels |
| DE19508858C2 (en) * | 1995-03-11 | 2001-05-17 | Schwerionenforsch Gmbh | Process for energy generation using inertial fusion using pellets |
-
1982
- 1982-08-02 GB GB08222215A patent/GB2104296B/en not_active Expired
- 1982-08-03 CA CA000408648A patent/CA1191283A/en not_active Expired
- 1982-08-16 JP JP57141997A patent/JPS5839986A/en active Granted
- 1982-08-17 FR FR8214203A patent/FR2515470B1/en not_active Expired
- 1982-08-18 DE DE19823230712 patent/DE3230712A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5839986A (en) | 1983-03-08 |
| GB2104296B (en) | 1985-05-30 |
| FR2515470A1 (en) | 1983-04-29 |
| FR2515470B1 (en) | 1986-03-14 |
| GB2104296A (en) | 1983-03-02 |
| DE3230712A1 (en) | 1983-03-03 |
| JPH028672B2 (en) | 1990-02-26 |
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