WO2013090342A1 - Procédé et appareil pour source radiofréquence (rf) peu coûteuse basée sur magnétrons verrouillés par injection 2 étages ayant un multiplexeur hybride 3 db pour commande précise et rapide de puissance et de phase de sortie - Google Patents

Procédé et appareil pour source radiofréquence (rf) peu coûteuse basée sur magnétrons verrouillés par injection 2 étages ayant un multiplexeur hybride 3 db pour commande précise et rapide de puissance et de phase de sortie Download PDF

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Publication number
WO2013090342A1
WO2013090342A1 PCT/US2012/069110 US2012069110W WO2013090342A1 WO 2013090342 A1 WO2013090342 A1 WO 2013090342A1 US 2012069110 W US2012069110 W US 2012069110W WO 2013090342 A1 WO2013090342 A1 WO 2013090342A1
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WIPO (PCT)
Prior art keywords
magnetron
frequency
phase
power
current
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PCT/US2012/069110
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English (en)
Inventor
Grigory KAZAKEVICH
Viyacheslav YAKOVLEV
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Muons, Inc.
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Publication of WO2013090342A1 publication Critical patent/WO2013090342A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/50—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field

Definitions

  • the present disclosure is generally related to an inexpensive radio frequency (RF) source based on magnetrons and, in particular, to an inexpensiv RF source based on 2-stage injection-locked magnetrons with a 3-dB hybrid combiner for precise and rapid control of output power and phase capable of driving superconducting RF cavities.
  • RF radio frequency
  • Intensity frontier high-energy superconducting linear accelerators have evoked a lot of interest the world over.
  • the high-intensity, high-energy accelerators increase the scientific potential of the country and serve as a basis for projects such as Accelerator- Driven Systems (ADS), which could lead to homeland energy independence and energy security because of their capability to incinerate the minor acdnides and long-lived fission products in radiotoxic waste and/or "spent" nuclear fuel.
  • ADS Accelerator- Driven Systems
  • the accelerators also can be used for utilization of Thorium as a nuclear fuel and can drive safe sub-critical nuclear reactors.
  • One of the general sub-systems of the ADS projects and the high-energy physics intensity frontier facilities is a high-energy, high-current, Continuous Wave (CW), superconducting proton linac.
  • CW Continuous Wave
  • high-power CW RF sources that are controlled in phase and in power, providing a precise stability of phase and amplitude of the accelerating field in each individual superconducting cavity (SC) of the linac, are desirable. Powering of each superconducting cavity separately and independently is desirable to suppress parasitic phase oscillations of the accelerating field in superconducting cavities, as described, for example, in H. Padamsee, j.
  • CW magnetrons based on commercial prototypes are potentially less expensive than any of the traditional RF sources such as high -power CW klystrons, IOTs, and solid-state amplifiers. This is all the more likely to be the case since CW magnetrons with power of tens to hundreds of kW are well within current manufacturing capabilities.
  • a high-power CW RF source providing a rapid control of output power and phase to feed the superconducting cavities of the intensity frontier linacs for high-energy physics facilities and ADS projects.
  • the RF source is based on inexpensive commercial CW magnetrons operating in an injection-locked mode with a 3-dB hybrid combiner.
  • injection-locking in magnetrons realizing operation of the forced oscillators is well known, but only recently have researchers demonstrated that the real capabilities of injection-locked magnetrons are acceptable to provide RF power to superconducting linacs.
  • the capabilitiesi ties of injection-locked magnetrons to provide RF power to superconducting linacs have been studied by considering transient processes describing the operation of a magnetron locked by a signal with varying frequency, which varies slowly in the magnetron frequency domain, as described, for example, in G.
  • the 3-dB hybrid combiner provides vectorial summing of power of both 2-stage
  • Rapid control of power feeding the superconducting cavity and, respectively, control of the accelerating voltage may be provided by an LLRF system managing a phase difference on the inputs of the 2-stage magnetrons.
  • the phase control of the accelerating voltage may be provided by a phase control on both 2-stage magnetrons inputs simultaneously.
  • the control of power and phase in the RF source is transformed into a control of phase and phase difference, which are quite linear and wideband, as described, for example, in G.
  • a device in a particular embodiment, includes means for providing a high-power continuous wave (CW) radio frequency (RF) source based on two injection-locked 2-stage CW magnetrons with outputs combined by a 3-dB hybrid combiner.
  • the device also includes means for operating the high-power CW RF source based on the two injection-locked 2-stage CW magnetrons with outputs combined by the 3-dB hybrid combiner to drive superconducting cavities of a linac.
  • the method also includes steps for operating the high-power CW RF source based on the two injection-locked 2-stage CW magnetrons with outputs combined by the 3-clB hybrid combiner to drive superconducting cavities of a linac.
  • CW continuous wave
  • RF radio frequency
  • FIG. 1 is a diagram illustrating a simplified conceptual scheme of a magnetron radio frequency (RF) source comprising two 2-stage (2 -cascade) continuous wave (CW) magnetrons operating in injection-locked mode and loaded by a. 3-dB hybrid combiner.
  • RF radio frequency
  • FIG. 2 is a diagram illustrating an embodiment of an apparatus including means for providing a high-power continuous wave (C W) radio frequency (RF) source based on two injection-locked 2-stage CW magnetrons with outputs combined by a 3-dB hybrid combiner and means for operating the high -power CW RF source based on the two injection-locked 2-stage CW magnetrons with outputs combined by the 3-dB hybrid combiner to dri ve superconducting cavities of a linac; and
  • C W continuous wave
  • RF radio frequency
  • FIG. 3 is a flow diagram of an illustrative embodiment of a method including steps for providing a high-power continuous wave (CW) radio frequency (RF) source based on two injection-locked 2-stage CW magnetrons with outputs combined by a 3-dB hybrid combiner and steps for operati g the high-power CW RF source based on the two injection-locked 2-stage CW magnetrons with outputs combined by the 3-dB hybrid combiner to dri ve superconducting cavities of a linac.
  • CW continuous wave
  • RF radio frequency
  • magnetron radio frequency (RF) source comprising two 2-stage (2 -cascade) continuous wave (CW) magnetrons operating in injection-locked mode and loaded by a 3-dB hybrid combiner is depicted and indicated generally, for example, at 100.
  • This RF source provides fast and rapid control of both power and phase.
  • FIG. 2 a diagram illustrating an embodiment of an apparatus is depicted and indicated generally, for example, at 200.
  • the apparatus 200 includes means for providing a high-power continuous wave (CW) radio frequency (RF) source based on two injection-locked 2-stage CW magnetrons with outputs combined by a 3-dB hybrid combiner 210 and means for operating the high-power CW RF source based on the two injection-locked 2-stage CW magnetrons with outputs combined by the 3-dB hybr d combiner to drive superconducting cavities of a linac 220.
  • CW continuous wave
  • RF radio frequency
  • FIG. 3 a flow diagram of an illustrative embodiment of a method is depicted and indicated generally, for example, at 300.
  • the method 300 includes steps for providing a high-power continuous wave (CW) radio frequency (RF) source based on two injection-locked 2-stage CW magnetrons with outputs combined by a 3-dB hybrid combiner 310 and steps for operating the high-power CW RF source based on the two injection-locked 2-stage CW magnetrons with outputs combined by the 3-dB hybrid combiner to drive superconducting cavities of a linac 320.
  • CW continuous wave
  • RF radio frequency
  • the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as those that are inherent therein. While the present invention has been depicted, described and is defined by reference to exemplary embodiments of the present invention, such a reference does not imply a limitation of the present invention, and no such limitation is to be inferred. The present invention is capable of considerable modification, alteration, and equivalency in form and function as will occur to those of ordinary skill in the pertinent arts having the benefit of this disclosure. The depicted and described embodiments of the present invention are exemplary only and are not exhaustive of the scope of the present invention.
  • Inexpensive RF source based on 2-stage injection-locked magnetrons with a 3-dB hybrid combiner for precise and rapid control of output power and phase
  • the high-intensity, high-energy accelerators increase scientific potential of country and serve as a basis for projects of the Accelerator Driven System (ADS) which lead to homeland energy independence because of their capability to incinerate the minor actinides and long-lived fission products of radiotoxic waste.
  • ADS Accelerator Driven System
  • the accelerators also can be used for utilization of Thorium as a nuclear fuel and can drive safe sub-critical nuclear reactors.
  • superconducting proton linac For operation of the accelerator are necessary high-power CW RF sources controlled in phase and in power providing a precise stability of phase and amplitude of the accelerating field in each individual superconducting cavity (SC) of the linac. Powering of each superconducting cavity separately and independently is necessary to suppress parasitic phase oscillations of the accelerating field in
  • the CW magnetrons based on commercial prototypes are potentially less expensive than the above-listed traditional RF sources the more so since the CW magnetrons with power of tens to hundreds kW are well within current manufacturing capabilities.
  • the RF source is based on inexpensive commercial CW magnetrons operating in injection-locked mode with a 3-dB hybrid combiner
  • the invented RF source has been experimentally modeled by CW injection-locked magnetrons, [8-10].
  • the experimental modeling demonstrated proof of principle of the invented RF ' source, controlled in phase and power quite rapidly that can be done by a suitable Low Level RF (LLRF) system.
  • LLRF Low Level RF
  • Analysis of the RF source modeling shows that the invented RF source will provide regulation of belter than 0.2 degree RMS and 0.2 percent RMS for phase and amplitude of the accelerating field, respectively, in the superconducting ca vi ty
  • magnetrons with outputs combined by a 3-dB hybrid is invented for intensity frontiers accelerators and ADS projects.
  • the RF source is controlled rapidly and precisely in power and phase.
  • the invented magnetron RF source consist of two 2-stage (2-cascade) CW magnetrons operating in injection-locked mode and loaded by a 3-dB hybrid combiner.
  • Figure 1 Simplified scheme of the magnetron RF source based on CW 2-stage injection- locked magnetrons.
  • the RF source provides fast control of power and phase.
  • the combiner provides vectorial summing of power of both 2-stage magnetrons feeding superconducting cavities of the linac. Rapid control of power feeding the cavity and, respectively, control of the accelerating voltage will be provided by a LLRF system managing phase difference on the inputs of the 2-stage magnetrons.
  • the phase control of the accelerating voltage is provided by a phase control on both 2-stage magnetrons inputs simultaneously.
  • the control of power and phase in the RF source is transformed into a control of phase and phase difference, which are quite linear and a wideband, [7].
  • SC Superconducting Cavities
  • Varying phase of the input signal for one of two-stage generator one can vary RF power on the output port of the hybrid. Varying phase of signals on both inputs properly one can vary both, the amplitude and the phase of the output signal.
  • the scheme is relatively inexpensive since the high-power commercial CW magnetrons are inexpensive and require relatively inexpensive and simple power supplies.
  • the scheme includes 2 modules, each contains of 3 active units: a solid state driver and two magnetrons. Other elements are passive; hence the scheme can be quite reliable.
  • Each Superconducting Cavity (SC) in the Project X klystron transmitter looks technically pulsed linac, requires a 1.3 GHz RF source with ⁇ 40 kW plausible, but the number of transmitters increases project pulsed power at 8% duty cycle. The utilization of costs.
  • development of a relatively inexpensive RF klystrons assumes driving 2 cryomodules (each with 8 source with adequate amplitude/phase dynamic range to cavities) from a single klystron with 640 kW pulsed excite each cavity independently is an important option power, 7.5 ms pulse duration, and 10 Hz repetition rate. for the Project X.
  • a concept of such RF generator is Such a klystron can be developed by industry, but the proposed and is considered in this work.
  • the SC filling time is limited by Lorentz forces.
  • Project X is an accelerator facility that is under possible to stabilize the cavity if total RF pulse duration development at Fermilab, [1], to support multiple physics (including filling and acceleration) does not exceed 10 ms programs at the intensity frontier.
  • Project X is based on a even when the external quality factor of the cavity is 3 GeV CW SC H " linac providing 3 MW of total beam 1 T0 7 .
  • the filling time is chosen power to the 3 GeV program for experiments in rare to be 3 ms, and the total RF pulse duration is 7.2 ms. processes and for nuclear physics related to ADS
  • the ILC SC bandwidth is about 100 Hz at the external program.
  • the cavity frequency proton beam at 60-120 GeV for long baseline neutrino deviations caused by a microphonic effect (so called the oscillation experiments.
  • 4.2% of the CW microphonics amplitude) is expected to be not greater H " beam will be redirected by a pulsed dipole magnet than 30 Hz.
  • the pulsed linac will utilize the standard ILC-type 1.3 cavity impedance, Q E is the cavity external Q-factor, / is GHz SC, [2], at the acceleration gradient of 25 MeV/m the cavity frequency, ⁇ ⁇ -10 degrees is the synchronous that is a realistic value for pulse operation.
  • the cavity phase, 6f is the microphonic amplitude.
  • the cavity is filling time and the full RF pulse duration are chosen to be detuned in order to compensate reactance of the beam. 3 ms and 7.2 ms, respectively.
  • the total number of SC For considered case the power P g is 31.5 kW per SC. required for acceleration of the H " at the given gradient is Taking into account power overhead for cavity control 200. Power to feed each cavity is approximately 40 kW.
  • the generator has to provide dynamic first one is based on a high power klystron feeding a range in power at least 40% to vary the SC accelerating number of SC (16 cavities in 2 cryomodules).
  • the scheme field in the range of ⁇ 20% in order to compensate the does not allow independent tuning of the phase and microphonics.
  • the bandwidth of the field variation has to voltage in the cavity that is necessary for weakly be at least 10 kHz which is the bandwidth of the feed relativistic particles.
  • the second option is based on forward and the feedback loops for the microphonic suppression control system.
  • FREQUENCY-LOCKED MAGNETRON U A it) is the magnetron time -dependent anode voltage
  • magnetrons [4, 5] initiated our concept to utilize magnetron nominal anode voltage, generators based on relatively inexpensive commercial is modulus of the magnetron cavity CW magnetrons. Since a magnetron is an auto-oscillator,
  • Equation (2) the frequency-locked magnetron provides high stability in was solved jointly with a similar one (without the noise frequency and phase if the forcing signal exceeds the first term) describing oscillations in the accelerating cavity harmonic noise signal in the magnetron cavity at the loaded by beam and fed by the magnetron through a magnetron excitation.
  • the magnetron model was reciprocal ferrite isolator with 0.4 dB and 18 dB of described by equation of the forced oscillation in the forward and inverse losses, respectively. Results of magnetron cavity coupled with a waveguide and loaded simulations and measurements were in an excellent by the magnetron current.
  • the second order equation was agreement, [4, 8], that proved correctness of the model.
  • V M and V FM are complex amplitudes
  • Figure 1 B- measured intrapulse frequency instability of of the oscillation in the magnetron cavity and forcing the frequency-locked magnetron relatively the forcing oscillation, respectively, Y 0M [1/Ohm] is the external signal frequency, left axis. E- measured variations of the magnetron current in relative units, right axis.
  • the noise source V Noise is added in the equation (2) to Table 1.
  • V M0 is the nominal magnetron (cavity) voltage
  • Excellent results in application of the frequency-locked can expect higher frequency and phase stability in the CW magnetron feeding a SC at a kW level of power
  • proposed magnetron RF source than it was described in are in agreement with results received with the 2.5 MW [4].
  • the concept [9] is based on a two-stage magnetron increment of the magnetron current, i.e. to variation of the generator concept in which the output power of the magnetron voltage, [4]. It allows utilization of simple and second magnetron is ⁇ 15 dB higher than the output power relatively inexpensive magnetron power supplies instead of the first one. Both magnetrons are coupled through of Advanced Modulators allowing fast variation of the phase ferrite circulators. The forcing signal exciting the output voltage (and current) as it was proposed in [5].
  • first (low power) magnetron is provided by a solid state For higher efficiency one needs to optimize the high- driver protected from the first magnetron output signal power CW magnetrons parameters considering range of with a phase ferrite circulator as well. To provide fast the power control.
  • Figure 2 Simplified scheme of the two-stage magnetron [6] Joint US-CERN-JAPAN international school on generators with fast control in amplitude and phase based frontiers in accelerator technology, 9-18 Sept. 1996, on CW commercial magnetrons. World Scientific, ISBN 981-02-3838-X.
  • the RF average power required for the CW proton and ion GeV-scale intensity frontier superconducting linacs for High Energy, HE, physics investigations and for Accelerator Driven System, ADS, projects is within the range of several MW to tens of MW.
  • Traditional CW RF sources as klystrons, lOTs, solid state amplifiers for such power are a significant fraction of the cost of these projects.
  • the concept most applicable for the proton and ion accelerators is the powering of each Superconducting Cavity, SC, by an individual Low Level RF (LLRF) vector controlled RF source.
  • the vector control includes a management of the SC feeding power and phase to keep optimized the phase and the amplitude of the accelerating field, [1-3] in each individual cavity to prevent the beam emittance growth, [4].
  • the CW power per cavity is within the range of tens kW to hundreds kW depending on the beam current.
  • the CW magnetrons based on commercial prototypes are potentially less expensive than the above-listed RF sources the more so since the CW magnetrons with power of tens to hundreds kW are well within current manufacturing capabilities.
  • a 2.45 GHz model of high-power RF transmitter based on injection-locked CW 1 kW magnetrons demonstrated features necessary for the vector control by a LLRF system.
  • magnetrons applicable to utilize the vector control necessary for powering of the superconducting cavities with electronic damping of parasitic phase
  • Fig. 1 Block diagram of the CW magnetron transmitter based on 2-cascade injection-locked magnetrons with a control in power and phase.
  • This transmitter configuration allows for the wideband phase and magnitude control following from accelerator RF vector regulation requirements.
  • the transmitter consists of two 2-cascade injection-locked magnetrons with outputs combined by a 3-dB hybrid.
  • the phase management is provided by a control of phase in both channels simultaneously, while the power management is provided by a control of phase difference on the inputs of the 2-cascade magnetrons, [8].
  • the modulator operating parameters are:
  • Fig. 5 The magnetron experimental module in which a CW magnetron operates as an injection-locked oscillator.
  • the CW magnetrons were mounted on the WR430 waveguide sections coupled with a waveguide-coax adapters.
  • the adapter and the section designs were optimized using CST Studio model to minimize reflection and maximize transmittance in the
  • ⁇ The transient process of phase modulation in the injection-locked magnetron takes of ⁇ 200 ns. This implies that a Low Level RF controller may have a closed loop bandwidth of ⁇ 100 kHz and will be able to suppress all expected system disturbances suppressing the parasitic frequency/phase modulation with the frequency as low as tens of Hz, as it was demonstrated in [10, 1 1] for magnetron operating in CW mode with a superconducting cavit in the feedback loop.
  • Fig. 10 Plot of control of combined power by phase difference in the combined injection-locked magnetrons.
  • ⁇ Bandwidth of the combined in power injection-locked magnetrons was measured with setup shown in Fig. 9, using phase modulation with amplitude of 20 degrees in the synthesizer.
  • the trombone ⁇ II length at the measurement was chosen to provide maximum power in the " ⁇ " combiner output.
  • Signal from the combiner output " ⁇ ” has been compared in phase with the synthesizer signal by the interferometer.
  • the phase response of the injection-locked magnetrons with power combining measured with the interferometer at the frequency of phase modulation of 30 kHz is shown in Fig. 11 .
  • Fig. 11 Trace of phase modulation measured for the magnetrons with power combining, injection- locked at phase modulation of the locking signal.
  • the modulation amplitude is 20 degrees and the modulating frequency is 30 kHz.
  • the measured frequency variation at t > 50-100 ms corresponds to parasitic frequency modulation in the injection-locked magnetron with effective amplitude of f eff « 22 Hz.
  • Fig. 16 Phase deviations of the 2-cascade injection-locked magnetron measured for pulse duration of ⁇ 5 ms at various values of the attenuator. Curves B and D show measured traces at 20 dB and 13 dB attenuator values, respectively.
  • phase deviations measured at ratio of the output power to locking power of 26.5 dB correspond to parasitic modulation with modulating effective frequency of f eff ⁇ 34 Hz.
  • phase deviations of the 2-cascade magnetron correspond to parasitic modulation with modulating frequency of f eff * 40 Hz.
  • phase response of the 2-cascade injection-locked magnetron model on the fasi 180 degrees phase flip has been measured using setup shown in Fig. 14, [ibid.].
  • the 180 degree phase flip in the TWT drive signal is accomplished, Fig. 17, with a pulse generator and double balanced mixer on the TWT amplifier input.
  • phase flip measured at ratio of the output range.
  • the injection- frontier SC accelerators of weakly-relativistic particles is locked two-stage CW magnetron can be used as an RF
  • the accelerating voltage be stable to within 1 %, [ibid] .
  • Project X could include an 8 GeV pulsed linac for future measurements [6, 7] for the locking power of -18 dB. 7; muon and/or neutrino facilities.
  • the pulsed linac will utilize the standard 1.3 GHz ILC- 7 type SC [2], with an accelerating field of 25 MV m.
  • the magnetron module was fed by a pulsed modulator
  • the pulse duration was 10 ms.
  • the magnetron was pre- excited by a precise CW oscillator with a TWT amplifier.
  • Figure 5b shows phase deviations in beginning locked magnetron in the pulsed regime. of the pulse, it can be seen that the time-to-lock is ⁇ 50 ⁇ .
  • magnetron modules were fed by a single modulator
  • the modulator pulse duration was
  • the first magnetron was
  • Time-to-lock of the 2-stage magnetron is ⁇ 50 ⁇ .
  • the transmitter consists of the required power are yet rather expensive as well.
  • the transmitter to power superconducting cavities is the ; phase control bandwidth in MHz range has been management of phase with a Low Level RF (LLRF) ; evaluated measuring transient time of the phase jump system generating a controlling signal which slowly ⁇ with a 2-stage CW magnetron model operating in pulsed varies phase on input of a 2-stage frequency-locked ⁇ regime.
  • LLRF Low Level RF
  • the state of the art superconducting linacs for proton in the locked magnetron allows numerical simulations of the frequency/phase deviations in time domain. Analysis and ion beams capable of accelerating protons and ions to
  • magnetron transmitter with a phase and power control. sub-critical reactors in nuclear power stations, to
  • the experimental facility was developed and built to : . emittances that may even result in beam loss.
  • the modulator, [9] provides concurrent operation of -
  • the Project X provides high-intensity 3 GeV the proton CW beam for rare processes experiments and for nuclear physics experiments related to ADS program.
  • the Project X should also provide a neutrino beam for long baseline neutrino oscillation experiments.
  • the neutrino beam requires 2 MW proton beam at the energy of 60-120 GeV, that will be produced by the FNAL Main Injector.
  • Beam pulse duration 4.3 ms
  • Feeding of a number of cavities from one RF source allows control of the vector sum of the cavity voltage only. This is very serious issue for weakly relativistic beam because of:
  • IOT manufacturers CPI (30 kW), E2V (16 kW -no longer in catalog), Thales (16 kW) and recently Mitsubishi (built 30 kW prototype for KEK ERL program)
  • Klystron efficiency is -60% and gain is -40 dB
  • Klystron manufacturers CPI sells a 'reliable' 1 1 kW tube and has a design for a 30 kW, 19 kV tube (would build one for 440 k$) and Toshiba is developing a 25 kW tube (probably for KEK)
  • JLab 12 GeV accelerator upgrade 1 .5 GHz, 13 kW CW klystrons were developed
  • Magnetron pulse power (including losses) : « 40 kW
  • Magnetron works as a forced oscillator, but NOT as an amplifier!
  • magnetron output power does not depend on the amplitude of the frequency/phase locking signal.
  • harmonic noise amplitude is enough for frequency/phase locking. Usually it's from -8 to « 20 dB in power scale,
  • Frequency/phase locked two-stage magnetron generator for a deep and rapid control of power and phase
  • Cost estimate for one transmitter $ 167 k
  • ⁇ Provides inclepeiideiit feeding of a separate SC with a rapid, Independent and deep control of amplitude and phase In each
  • Ariirie history A laboratory-size Free Electron Laser (FEL) driven by a classical S-band inicrotron fed by a 2.5 MW magnetron d c ived 24 January 201 1 generates terahertz radiation lunabie in a wide range.
  • the FEL provides output pulse power of ⁇ SO W in the Received :n revised form wavelength range of 100- 300 ttm with a pulse duration oi ' 2-4 fis.
  • the FEL parameters are available due to 19 April 201 1 stabilization of the accelerated beam current and the magnetron frequency. The latter is stabilized by the Accented 19 April 2011
  • Keywords simple RF stabilizing scheme provides the r.m.s. magnetron frequency instability, ⁇ » 0-13 kHz relative to Magn ron the reference frequency at the frequency pulling bandwidth of 0.43 - 0,85 MHz and at the initial power of the frequency locking
  • the last one was simulated, solving a system of the abridged die cathode, which results in incremental heating of the emitting equations [5,6], lor the transient state of the magnetron and the surface and also in incremental emission current [4j.
  • the accelerating cavity loading current contained emission current in the high-current microtron results in an increin the system of equations was computed by 2-0 tracking for ail mental beam loading causing a drop of the accelerating field in the orbits of the microtron.
  • the magnetron frequency also has been microtron cavity; this results in a drop of the accelerated current measured with a heterodyne technique [6-S]. Results of the compuduring the macro-pulse that is inadmissible lor FEL operation.
  • the resonance electrons appear with a delay At ⁇ 3rc ⁇
  • the current density of the LaB s single crystal emitter can be Qa ⁇ 3 ⁇ 4/( ⁇ -;- :) KC.
  • Q iJC -9800 is the measured value of the expressed as a function of r, ⁇ considering the Schottky effect as accelerating cavity wall Q-factor.
  • ⁇ —5,4 (measured value) is the cavity coupling coefficient and ; ; - 0.174 ⁇ 5 is the accelerating
  • TIF (sin(feo£/2)/(feoi./2)) is the transit-time
  • UA_ T ⁇ 0.8UA_H is the threshold of the anode voltage. .(ton.tl o ⁇ . feoXn(f(le.t))Sm( ⁇ »t)df.
  • microtion cavities are expressed as The accelerating frequency drift, curve D. computed above.
  • M c— 0,4 dit is the transfer coefficient from the magnetron reference frequency drift with very high accuracy.
  • M — 1 S.0 dB is the transfer coeffithe very good stabilizing properties of the described simple cient from the microtfon cavity to the magnetron. Both coeffifrequency- locking scheme and confirms that the variation of the cients characterize the ferrite isolator.
  • accelerating (the reference) frequency at the internal injection is
  • V K and y iM can be expressed as function;; of caused by the incremental beam loading in the accelerating cavity by considering Eqs. (13) and ( 14); and is a result of the cathode overheating from the back-streaming electrons.
  • curve B curve B.
  • Fig, 8. shows the time required to stabilize the magnetron. The time is 3 ⁇ 4 1 .5 ps at the existing parameters of the
  • the time-dependent amplitude of the wave reflected from the frequency for the plots B and D in the time interval 2,5-6,5 p.s, accelerating cavity has been measured using a 20 dB waveguide when the magnetron is well stabilized, is s; 19 ItHz. It corredirectional couplet at various values oi ' the magnetron-acceleratsponds to a computed magnetron frequency instability relative to ing cavity detuning parameter. the stabilizing frequency better than 7 > ⁇ : 10 " b at the magnetron
  • Fig. 10 shows excellent coincidence of the measured 0.85 0.01:5 0.58 4.64 x U a magnetron frequency variations with the computed reference
  • the plot r.m.s. frequency instability in relative units vs. the Af value. demonstrates very high intrapulse frequency stability of the Analysis of die measured plot B in Fig. 1 1 and analysis of data magnetron with the frequency locking scheme utilizing the from Table 1 show high stabilizing properties of the simple frequency pulling.
  • Curve £ shows the magnetron current variafre uency-locking scheme while the magnetron without the tions in relative units during the pulse.
  • the magnetron current frequency locking has the measured frequency pushing of has been measured using a calibrated wide-hand current trans* O.t MHz/A in the considered time interval [ 13j. Hence the former.
  • the ripples in the magnetron current with amplitude less considered frequency-locking scheme improves the frequency than 1.5% result from the non-uniformity of the multi-ceil charstability of the magnetron ⁇ 30-50 times, depending on the ging line of the magnetron modulator. frequency pulling bandwidth.
  • magnetron frequency are a result of the magnetron current Acknowledgment
  • Gavriiov in: Proceedings of the PAC 2001 Conference, i ag , 200 : , pp. 2739--2741.
  • a magnetron-driven microtron injector has been developed for a terahertz free electron laser (FEL).
  • FEL terahertz free electron laser
  • An internal injection system was chosen for the microtron to achieve a compact and inexpensive design.
  • the system provides acceleration of electrons with low emittance and energy spread that is highly important for the FEL.
  • the intrapuise instabilities of the accelerated current and the bunch repetition rate inherent to the injection system make problems for the FEL operation.
  • Simulations of the beam dynamics and the transient process allow one to compute the load characteristic of the accelerating cavity and the time- dependent accelerated current.
  • the simulation techniques also allow one to calculate time- dependent deviations of the magnetron frequency in the coupled system of the accelerating and magnetron cavities, as well as deviations in the bunch repetition rate.
  • the computations validate proposed concepts for increasing the intrapuise current stability with appropriate time-dependent variation of the magnetron power and decreasing the bunch repetition rate instability through a simple microwave scheme utilizing the microtron accelerating cavity concurrently as an external stabilizing resonator for the magnetron.
  • the realized concepts and optimization of the microtron regimes using the simulated phase motion of the accelerated bunch provide stable operation of the terahertz FEL, tunable in the range of 1-3 THz with extracted macropulse power up to 50 Watts at the raacropulse energy of 0.2 mj.
  • microtron magnet allows one to extract the accelerated erated current has a fiat top providing intrapuise stability of electrons from various orbits; this varies kinetic energy the beam current suitable for FEL operation.
  • the of the beam approximately from 4.4 to 6.5 MeV and incremental magnetron current deteriorates the intrapuise provides generation of the terahertz FEL in wide range. frequency stability of the magnetron autogenerator be ⁇
  • the regime of the microtron requires the macropulse cause of the frequency pushing. Correspondingly the emission current of ⁇ 1 A. Such a value of the emission bunch repetition rate stability becomes worse, leading to current causes noticeable pulsed overheating of the catha drop of the lasing energy. Note that at lower energy the ode surface because of the back- sire anting electrons.
  • the microtron at optimal regime accelerates higher current; phenomenon in the microtron with internal injection
  • E( r, t) is the electric field acting on the electron at the
  • Microtron permanent magnetic field 0.1065 T point with coordinate r arid the time t, i> is the velocity of
  • B includes the rf component in the accelerating cavity and the permanent microtron field.
  • a simple microwave scheme based on the frequency is the cavity loading current. This allows one to compute pulling in the magnetron and utilizing the reflected wave the accelerated current in the time domain considering the from the accelerating cavity was developed to stabilize the loading current effect. Moreover, this allows one to commagnetron frequency and the bunch repetition rate. The pute frequency and phase deviation of the accelerated scheme was numerically simulated using the transient state bunches that are important for the FEL injector.
  • FEL macropuise energy ⁇ 0.2 mJ was obtained employwhere I o is the maximum of the cathode emission current. ing the optimization.
  • the current density j n is nonzero only inside the cavity.
  • the concepts of the intrapulse stabilizations realized in The first harmonic of the current density is equal to the magnetron-based microtron driving the terahertz FEL N-l
  • i c (t) is the normalized dimensionless time- the TMoio mode of the accelerating field in a cylindrical
  • M dependent slowly varying emission current
  • the particle is located at the point with coordinates of y n — e ( r) is a distribution of normalized electric field in 0, XM Q ,,, t), and ⁇ ,, (% impart. f) having velocity of £> sing(3 ⁇ 4 token, t). the cavity, and v is the average velocity of the electron
  • FIG. 1 2D tracking in median plane of the microtron. In the c left corner is shown the tracking of the first orbit and the layout of the accelerating cavity having narrow radiai slits for passage arctan- of the electrons.
  • the magnetron frequency of 2.8 GHz.
  • the electrons hitting (2) are shown detailed plots of the loading current and the cavity wails (inside or outside of the cavity) were extracted current phases, ⁇ ⁇ and ⁇ ⁇ respectively, in the omitted in the tracking. neighborhood of the microtron operating conditions.
  • a transient state of the microtron cavity has been computed based on the slowly varying envelope approximation (S VEA) [S] considering loading of the cavity caused by the electron beam under acceleration.
  • S VEA slowly varying envelope approximation
  • FIG. 2. Normalized amplitudes of the loading current
  • Curve 1 shows that the amplitude of the accelerated current is reduced almost by half at the end of the macro- pulse because of an increase of the emission current, that causes the incremental beam loading in the accelerating cavity.
  • V, fMVl pulse by tuning the modulator charging line to provide linear increments of the magnetron current by ⁇ 10%.
  • FIG. 3. Phases of the loading current, ⁇ x / admir, and the Figure 5 shows the calculated shape of the accelerated extracted current, ⁇ ⁇ , as functions of the accelerating cavity current, curve 2, for the measured incremental magnetron voltage, V c . current, curve 1.
  • FIG. 4 Calculated shape of the accelerated current, curve I, in the forward wave, respectively, Y — 2.363 X
  • FIG. 5 (Color) Calculated, curve-: 2, relative units, and meaHere (i) i A (t) is the normalized dimensionless time sured, curve 3, right scale, acceierated current at she 12th orbit
  • the relative electron conductance y M depends on the anode voltage U A and the modulus of the magnetron cavity
  • the ano is equal to
  • the output power of the magnetron is equal to tron current because of the frequency pushing in the magnetron.
  • the voltage of the reflected wave in the waveguide is
  • V M — VpM- netron current are in the range of - « 0.8 MHz during the macropulse in operation with a passive load.
  • V RM The expression for V RM can be presented as
  • the developed microtron-driven terahertz PEL utilizes an optical resonator with the length determined from the V RM - VRM * exp(i ⁇ ⁇ p m ).
  • the time-dependent deviations of the magnetron frequency wavelength of the accelerating voltage, and f b is the bunch can be calculated from repetition rate of the accelerated current.
  • Fig. 7 are shown the calculated and the measured ing by ⁇ 0.8 mm during the macropulse. This value is intrapuise inagnetron frequency deviations for the magneinadmissibly large for the terahertz FEL operating in the tron loaded by a passive load ( V FM — 0, so V R M — V M ). wavelength range of 0.1-0.35 mm.
  • the magnetron intrapuise frequency deviations were netron frequency.
  • the scheme is based on the frequency measured using a heterodyne method.
  • the magnetron pulling in the magnetron through the wave reflected from was loaded by the passive matched waveguide load.
  • a the accelerating cavity; in other words, the accelerating directional coupler with directionality of ⁇ 20 ciB was cavity serves concurrently as an external stabilizing resoused to measure the deviation of the magnetron frequency nator for the inagnetron.
  • the reflected wave passes through in the forward wave.
  • the attenuated wave from the maga ferrite insulator, having limited inverse loss of ⁇ 18 dB netron was mixed with the 2.793 GHz signal of a syntheat the magnetron pulse power of 1,7-2 MW.
  • Such loss sizer and periods of the difference frequency were provides an acceptable level of the passing wave for the measured during the macropulse with a 2 Gs/s digital frequency pulling in the magnetron.
  • the microwave oscilloscope The measured results were averaged over microtron system was optimized in length.
  • a layout of the i 0 macropolses. The accuracy of the measured frequency microtron and the microwave system based on the MI- deviations with this method is ⁇ 3-5 kHz for the 100 ns 456A magnetron is shown in Fig. 8.
  • FIG. 9. (Color) Calculated (solid lines) and measured (bold solid
  • V Vr - V f ' C> V (13 ) tron frequency are shown in Fig. 9 by solid lines.
  • the solid lines with error bars are the measured magnetron frequency
  • the magnetron was loaded by the accelerating cavity through the ferrite insulator.
  • the frequency deviations were measured in the forward wave with the directional coupler.
  • the measurements were done using the heterodyne method as described above at an accel on 12th
  • curve 4 are caused by deviations of the magnetron current during the macropulse with relative amplitudes of - 1.5% (corresponding to ⁇ 0.2% in the modulator pulse
  • the cavity voltage can be written in following form: FIG. 10. (Color) B— deviations of the frequency in the micro ⁇
  • V c (t) V c (t) ⁇ expj ⁇ ip c (f)]. (16) tron accelerating cavity. C— bunch repetition rate deviations of the extracted current.
  • Vci is the time-dependent modulus of the cavity
  • the extracted current is proportional to the time- are caused by ripples of the magnetron current because of dependent emission current, the dimensionless amplitude
  • Deviations of the frequency in the microtron accelerat The establishment of the equilibrium phase is continued ing cavity during the tnacropulse are computed using the during the increase of the V c amplitude from a minimum following expression: value, acceptable for acceleration of the electrons over all orbits in the microtron and corresponding to 0.556 MV,
  • phase motion of the extracted bunches are computed as
  • the terahertz FEL power signal varying the detuning electron beam extracted from the 12th orbit was transparameter.
  • the cavity signal containing inforage was kept constant.
  • the accelerated current also was mation about the bunch repetition rate has been measured kept, constant with accuracy better than 3.5% to keep a using a heterodyne method in the manner described above.
  • microtron age emission current ⁇ 1.1 A.
  • modulator charging operating parameters were optimized to get minimal incresystem provided constant charging voltage with accuracy ments of the emission current at the accelerated macrobetter than 0.1 %.
  • pulse current 42 mA.
  • the lasing macropulse power was
  • the measured intrapulse magnetron frequency Plot b in Fig. 12 shows the measured drop of the lasing deviations are plotted by dots with the same color. energy with an increase of the detuning parameter.
  • the plotted curves show thai the measured deviations of drop is a result of the additional frequency modulation in the magnetron frequency, with a period of—0.6 ⁇ $ and an the bunch repetition rate that is caused by variation of the amplitude of—30 kHz, are in fact similar in shape for ail equilibrium phase during the transient process.
  • the plots in the inset (a) show a noticeable growth of the measured repetition rate of the extracted bunches in the buildup time with an increase of the detuning parameter.
  • the amplitude of optimized for minimum detuning in the system magnetron- the oscillation strongly depends on the detuning parameter, accelerating cavity at a given accelerated current injected as was noted above, in agreement with the beam dynamic into the FEL, In this case, one can provide maximum consideration. energy in lasing and maximum lasing macropulse duration.
  • FIG. 11 (Color) Measured deviations in the bunch repetition 0.52; 2— ⁇ - 0.69; 3— e - 0,74; 4— e - 0.88; 5— shape of the rate (bold solid lines with error bars) and in the magnetron beam line current, (b) Variation of the lasing macropulse energy frequency (dots) for various values of the detuning parameter, e. at wavelength of 1 10 ⁇ . ⁇ vs the detuning parameter.
  • microtron provides operation of the FEL [8] D. PL Whittum, Frontiers of Accelerator Technology, in the range of 1-3 THz with extracted lasing power of 30- U.S.-CERN-Japan International School, Japan, edited by
  • microtron injector has demonstrated stable and reliable [10] G. M. Kazakevitch. Y U. Jeong. B. C. Lee. and J. Lee, operation for users for more than 5 years. Nucl. lnstrum. Methods Phys. Res., Sect. A 483, 331
  • the microtron has been improved through stabilization of the beam current and the magnetron frequency.
  • the beam current was stabilized during the macro-pulse by increasing the magnetron anode current.
  • the pulse stabilization of the emission current makes possible the microtron operation with the maximal accelerated current, without risk of break-downs in the cavity and keeps the instability of the accelerated current at approximately 1 % during long-time experiments.
  • the magnetron frequency was stabilized using the microtron accelerating cavity as a stabilizing external resonator in a simple scheme that involved the cavity loading of the magnetron through a ferrite insulator.
  • the scheme provides stabilization of the magnetron frequency with a coefficient of 3.5.
  • the stabilization of current and the frequency at the microtron FIR FEL-injector provides satisfactory intrapulse stability of the extracted lasing power of 40-50 W in the FIR macro-pulse having duration of 3-4 ⁇ and a long-time pulse-to-pulse instability of the FIR pulse energy in the range of ⁇ 10%. Results of simulations of the stabilization based on the microtron operating parameters and measured results are presented and discussed.
  • E-mail address gkazakevitch@yahoo.com beam the emission current of the microtron has (G.M. Kazakevitch). an increase of 25-30% during the macro-pulse
  • J ⁇ (t, r) is the first-time harmonic of current in the microtron provides a pulse-to-pulse the current density, which depends on the emission instability of the lasing energy in the range of current 3 ⁇ 4( an ⁇ 3 coordinates and velocities of the ⁇ 10% during a long-time operation.
  • electrons passing through the cavity, w* are the first-time harmonic of current in the microtron.
  • L is the cavity us to develop the inexpensive, stable, wide-band length
  • vo is the average velocity of the tunable FEL, having tens of Watts in the extracted electron.
  • ⁇ t/ co
  • fco the fill -time of the cavity
  • ⁇ 2o is the wall quality factor
  • coo is the circular
  • eigen frequency of the cavity i c is the cavity Fig. 1.
  • 1 Measured macro-pulse emission current, vert, scale coupling coefficient, VQ and pc are complex is 250mA/div.
  • 2 calculated shape of the accelerated current by a constant magnetron current during the macro-pulse
  • 3 amplitudes of the oscillation in the cavity and in calculated shape of the accelerated current by the incremental the forward wave, respectively
  • 3 ⁇ 4h is the shunt magnetron power
  • 4 measured accelerated current by the impedance of the cavity
  • J is the complex incremental magnetron power
  • vert scale is lOmA/div.
  • the shape of the accelerated current for and inexpensive magnetron generator which feeds measured time-dependent magnetron and emission the microtron cavity.
  • the electron frequency drift currents was calculated using the equation system caused by the incremental anode current in the including the abridged equation for the acceleratmagnetron and deteriorating the bunch repetition ing cavity (1) and a similar one, which described rate stability was suppressed by means of a the transient state in the magnetron this equation simplified scheme.
  • the scheme is based on the differs from Eq. (1) with the noise term [5].
  • the frequency pulling in the magnetron through the loading current for the microtron cavity was wave reflected from the accelerating cavity, which calculated by the tracking in the median plane up also serves as an external stabilizing resonator. to 12th orbit.
  • the magnetron current was meaThe reflected wave passes through a ferrite sured using a calibrated wide-band current transinsulator, having inverse losses of 3 ⁇ 4 18 dB by the former.
  • the measured shape of the top of the power of 1.7-2 MW, providing an acceptable level magnetron macro-pulse current is shown in of the passing wave for the frequency pulling.
  • the Fig. 2(c). microtron-microwave system has been optimized in the length.
  • the simulations and the measurements have been conducted for both cases of the magnetron load: with the accelerating cavity loaded by the electron current and with a passive matched waveguide load.
  • curves (b) are respective to the passive matched load.
  • Curve (c) deviations during the macro-pulse in the coupled demonstrates the shape of the top of the magnetron pulse magnetron-microtron cavity system and the magcurrent (relative units).
  • netron-passive load system were done using a 118 G.M. Kazakevitch et al. I Nuclear Instruments and Methods in Physics Research A 528 (2004) 115-119 temporal heterodyne method [6], providing the on a fast ADC measuring the emission pulse relative inaccuracy of 3 ⁇ 4 10 ⁇ 6 in the time interval current. The system averages the data for a few of 3 ⁇ 4 100 ns.
  • the deviations were measured in the pulses, analyzes the data and tunes the cathode forward wave using the 20-dB directional coupler. filament stabilizer.
  • filament stabilizer By the randomized stripping of The results are shown in Fig. 2 by dotted lines (a) acceleration, the stabilization system tunes the and (b), respectively.
  • the shape of the top of the cathode filament stabilizer to prevent breakdowns.
  • magnetron macro-pulse current is plotted in The system provides long-time pulse-to-pulse Fig. 2(c) in relative units. instability of the emission current ⁇ 1 % .
  • the magnetron current oscillation has a the temporal heterodyne method with the monrelative value of s i % in the amplitude, that itoring cavity [6] had a relative value of ⁇ 8 x l0 ⁇ 5 . corresponds to the oscillation in the magnetron
  • the emission current was chosen to provide pulse voltage with the level of ⁇ 0.2%, and causes operation in the neighborhood of the maximum the "slow" oscillation in the magnetron frequency of the microtron volt-ampere characteristic.
  • This with the relative value of 3 ⁇ 4 10 ⁇ 5 and «4 x 10 ⁇ 5 by provides the value of the beam current in the operation with the stabilizing cavity and the beamline at the undulator entrance in the range of passive load, respectively. 40-42 m A by extraction of electrons from the 12th orbit and in the range of 44-46 mA by extraction from the 10th orbit.
  • Pulse stabilization of the emission current instability of the current had a value of ⁇ 1 mA.
  • Simple, inexpensive and reliable classical magnetron-driven microtron has been upgraded to use as an injector of the compact wide-band FIR FEL.
  • the developed stabilization of the microtron operation provides long-time stability in the lasing iZ
  • pulse shape of the beamline current, vert, scale is 20mA/div.

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Abstract

Selon un mode de réalisation particulier, la présente invention porte sur un dispositif qui comprend un moyen pour fournir une source radiofréquence (RF) à onde continue (CW) haute puissance basée sur deux magnétrons CW 2 étages verrouillés par injection ayant des sorties combinées par un multiplexeur hybride 3 dB. Le dispositif comprend également un moyen pour mettre en œuvre la source RF CW haute puissance basée sur les deux magnétrons CW 2 étages verrouillés par injection ayant des sorties combinées par le multiplexeur hybride 3 dB pour commander des cavités supraconductrices d'un accélérateur linéaire. Selon un autre mode de réalisation particulier, la présente invention porte sur un procédé qui comprend des étapes pour fournir une source radiofréquence (RF) à onde continue (CW) haute puissance basée sur deux magnétrons CW 2 étages verrouillés par injection ayant des sorties combinées par un multiplexeur hybride 3 dB. Le procédé comprend également des étapes pour mettre en œuvre la source RF CW haute puissance basée sur deux magnétrons CW 2 étages verrouillés par injection ayant des sorties combinées par le multiplexeur hybride 3 dB pour commander des cavités supraconductrices d'un accélérateur linéaire.
PCT/US2012/069110 2011-12-12 2012-12-12 Procédé et appareil pour source radiofréquence (rf) peu coûteuse basée sur magnétrons verrouillés par injection 2 étages ayant un multiplexeur hybride 3 db pour commande précise et rapide de puissance et de phase de sortie WO2013090342A1 (fr)

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CN109936906A (zh) * 2017-12-15 2019-06-25 中国科学院大连化学物理研究所 光阴极电子枪射频同步慢飘抑制装置
CN110275199A (zh) * 2019-06-18 2019-09-24 中国科学院近代物理研究所 一种共振肖特基探针装置及其使用方法
CN110988615A (zh) * 2019-11-14 2020-04-10 广东电网有限责任公司 一种基于奇异谱分析的gis局放信号降噪方法
KR20200053509A (ko) * 2017-08-28 2020-05-18 뮤온스 인코포레이티드 내부 변조를 가진 마그네트론 rf 소스를 사용한 펄스 전력 생성
US11123921B2 (en) 2018-11-02 2021-09-21 Fermi Research Alliance, Llc Method and system for in situ cross-linking of materials to produce three-dimensional features via electron beams from mobile accelerators
US11224918B2 (en) 2018-01-19 2022-01-18 Fermi Research Alliance, Llc SRF e-beam accelerator for metal additive manufacturing
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US10477668B2 (en) 2014-09-19 2019-11-12 Fermi Research Alliance, Llc Vector control of radio frequency signal in narrow band loads driven by injection locked magnetron using carrier amplitude modulation by spectral energy spreading via phase modulation
US20170280549A1 (en) * 2014-09-19 2017-09-28 Brian E. Chase Vector control of radio frequency signal in narrow band loads driven by injection locked magnetron using carrier amplitude modulation by spectral energy spreading via phase modulation
WO2016043783A1 (fr) * 2014-09-19 2016-03-24 Fermi Research Alliance, Llc Commande de vecteur d'un signal rf dans des charges à bande étroite entraînées par magnétron à verrouillage par injection
US10070509B2 (en) 2015-09-29 2018-09-04 Fermi Research Alliance, Llc Compact SRF based accelerator
US10993310B2 (en) 2015-09-29 2021-04-27 Fermi Research Alliance, Llc Compact SRF based accelerator
US10390419B2 (en) 2015-09-29 2019-08-20 Fermi Research Alliance, Llc Compact SRF based accelerator
JP2020532084A (ja) * 2017-08-28 2020-11-05 ミューオンズ インコーポレイテッドＭｕｏｎｓ，Ｉｎｃ． 内部変調機能付きマグネトロンｒｆ源を使用したパルス電力生成
JP7201667B2 (ja) 2017-08-28 2023-01-10 ミューオンズ インコーポレイテッド 内部変調機能付きマグネトロンｒｆ源を使用したパルス電力生成
KR102642278B1 (ko) 2017-08-28 2024-02-28 뮤온스 인코포레이티드 내부 변조를 가진 마그네트론 rf 소스를 사용한 펄스 전력 생성
KR20200053509A (ko) * 2017-08-28 2020-05-18 뮤온스 인코포레이티드 내부 변조를 가진 마그네트론 rf 소스를 사용한 펄스 전력 생성
CN109936906A (zh) * 2017-12-15 2019-06-25 中国科学院大连化学物理研究所 光阴极电子枪射频同步慢飘抑制装置
CN109936906B (zh) * 2017-12-15 2024-03-08 中国科学院大连化学物理研究所 光阴极电子枪射频同步慢飘抑制装置
US11224918B2 (en) 2018-01-19 2022-01-18 Fermi Research Alliance, Llc SRF e-beam accelerator for metal additive manufacturing
US11123921B2 (en) 2018-11-02 2021-09-21 Fermi Research Alliance, Llc Method and system for in situ cross-linking of materials to produce three-dimensional features via electron beams from mobile accelerators
US11878462B2 (en) 2018-11-02 2024-01-23 Fermi Research Alliance, Llc Infrastructure-scale additive manufacturing using mobile electron accelerators
CN109743103A (zh) * 2019-02-01 2019-05-10 福州大学 基于elm的fbg传感网络节点故障修复方法
CN109743103B (zh) * 2019-02-01 2021-07-27 福州大学 基于elm的fbg传感网络节点故障修复方法
CN110275199A (zh) * 2019-06-18 2019-09-24 中国科学院近代物理研究所 一种共振肖特基探针装置及其使用方法
US11465920B2 (en) 2019-07-09 2022-10-11 Fermi Research Alliance, Llc Water purification system
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