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RSS2003 Vol. 15, No. 01
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2003,
15.
Abstract:
Using a laser longpath experimental system which White cell with CO2 of 80 or 40 kPa, the highresolution absorption spectra of CO2 near 1.315μm have been recorded and the spectroscopic line parameters are obtained. They are comparable with the data in HITRAN 2k. The absolute absorption is determined by means of path differencing. The total absorption cross section is (0.23~0.29)×10-24cm2 for CO2 at 7 603.138 5cm-1, and the absorption cross section comes of the spectroscopic lines is 0.18×10-24cm2. There is continuum absorption in this region and the continuum absorption cross section is (0.05~0.11) ×10-24cm2. The error is discussed as well.
Using a laser longpath experimental system which White cell with CO2 of 80 or 40 kPa, the highresolution absorption spectra of CO2 near 1.315μm have been recorded and the spectroscopic line parameters are obtained. They are comparable with the data in HITRAN 2k. The absolute absorption is determined by means of path differencing. The total absorption cross section is (0.23~0.29)×10-24cm2 for CO2 at 7 603.138 5cm-1, and the absorption cross section comes of the spectroscopic lines is 0.18×10-24cm2. There is continuum absorption in this region and the continuum absorption cross section is (0.05~0.11) ×10-24cm2. The error is discussed as well.
2003,
15.
Abstract:
Expressions describing couplings between different emitters of a diode laser array (DLA), positioned in an external cavity (EC), have been deduced. The results show that: the increase of the EC length reduce the differences between these coupling coefficients, which is favorable to achieve the so called “parallel coupling” at the expense of the effectiveness of the EC; decreasing the reflection coefficient at the front facet of the DLA is favorable to achieve phase locking in EC; the more parallelly coupled the emitters are, the lower the allowed reflection coefficient at the front facet of the DLA is.
Expressions describing couplings between different emitters of a diode laser array (DLA), positioned in an external cavity (EC), have been deduced. The results show that: the increase of the EC length reduce the differences between these coupling coefficients, which is favorable to achieve the so called “parallel coupling” at the expense of the effectiveness of the EC; decreasing the reflection coefficient at the front facet of the DLA is favorable to achieve phase locking in EC; the more parallelly coupled the emitters are, the lower the allowed reflection coefficient at the front facet of the DLA is.
2003,
15.
Abstract:
Photoluminescence (PL) and optical transient current spectra (OTCS) were observed from GaAs/AlGaAs quantum wells structure excited by midinfrared free electron laser (FEL) irradiation. The experimental results of PL showed that the characteristic PL peak of quantum wells shifted to longer wavelength (red shift) and the intensity decreased much after FEL irradiation. From the analysis of OTCS, extrinsic defects were found after FEL irradiation. This paper author discusses the results and comparison with that of electron irradiation．
Photoluminescence (PL) and optical transient current spectra (OTCS) were observed from GaAs/AlGaAs quantum wells structure excited by midinfrared free electron laser (FEL) irradiation. The experimental results of PL showed that the characteristic PL peak of quantum wells shifted to longer wavelength (red shift) and the intensity decreased much after FEL irradiation. From the analysis of OTCS, extrinsic defects were found after FEL irradiation. This paper author discusses the results and comparison with that of electron irradiation．
2003,
15.
Abstract:
A series of the output of the HgCdTe ( PC ) detector is observed when irradiated by CW 1 319 nm laser and 10 600nm laser respectively. The saturation threshold of the HgCdTe(PC) detector irradiated by CW 1 319nm laser is given; some phenomena were observed when the HgCdTe(PC) detector was irradiated by offband CW CO2 laser which are much different from that irradiated by inband light; the results of measurements have been analyzed. Finally, the response character of the PCtype HgCdTe detector to the irradiation of inband and offband is summarized respectively.
A series of the output of the HgCdTe ( PC ) detector is observed when irradiated by CW 1 319 nm laser and 10 600nm laser respectively. The saturation threshold of the HgCdTe(PC) detector irradiated by CW 1 319nm laser is given; some phenomena were observed when the HgCdTe(PC) detector was irradiated by offband CW CO2 laser which are much different from that irradiated by inband light; the results of measurements have been analyzed. Finally, the response character of the PCtype HgCdTe detector to the irradiation of inband and offband is summarized respectively.
2003,
15.
Abstract:
Owing to the PTD effect in the lenses of spatial filter, large temporal front distortion of femtosecond pulses occurs in the spatial filter. In this work, in order to design a spatial filter which is applicable to high power femtosecond laser system, PTD of achromatic doublet or separated doublet is calculated and special spatial filter is discussed in which achromatic doublet or separated doublet replace the single lens. PTD of the special spatial filter is little so temporal front distortion of femtosecond pulse in laser system is eliminated or reduced.
Owing to the PTD effect in the lenses of spatial filter, large temporal front distortion of femtosecond pulses occurs in the spatial filter. In this work, in order to design a spatial filter which is applicable to high power femtosecond laser system, PTD of achromatic doublet or separated doublet is calculated and special spatial filter is discussed in which achromatic doublet or separated doublet replace the single lens. PTD of the special spatial filter is little so temporal front distortion of femtosecond pulse in laser system is eliminated or reduced.
2003,
15.
Abstract:
In high energy X-ray radiography system , CsI convertor is usually used to convert the X-ray image into a visible image which can be recorded by other high sensitive image system . The scattering light from the inner side of the convertor can reduce the image contrast and the spacial resolution will degrade. In the paper ,one evaluation method about the influence on the image contrast is set up and some calculated results are given to show this . The tests have proved that the process on the back side of the convertor is the most important thing and that the scattering coefficient of the back side must be reduced to a very small level to keep the image contrast．
In high energy X-ray radiography system , CsI convertor is usually used to convert the X-ray image into a visible image which can be recorded by other high sensitive image system . The scattering light from the inner side of the convertor can reduce the image contrast and the spacial resolution will degrade. In the paper ,one evaluation method about the influence on the image contrast is set up and some calculated results are given to show this . The tests have proved that the process on the back side of the convertor is the most important thing and that the scattering coefficient of the back side must be reduced to a very small level to keep the image contrast．
2003,
15.
Abstract:
In our experimental research on laser irradiating semiconductor photodetectors, chaos in the PV-type HgCdTe detectors irradiated by a mild stable continuous wave laser is found. The detectors will give chaotic output when the irradiation power density of laser increases above the saturation threshold of them. Chaos is diagnosed by determining the power spectrum and Lyapunov exponent from the output signal of the detectors in this paper．
In our experimental research on laser irradiating semiconductor photodetectors, chaos in the PV-type HgCdTe detectors irradiated by a mild stable continuous wave laser is found. The detectors will give chaotic output when the irradiation power density of laser increases above the saturation threshold of them. Chaos is diagnosed by determining the power spectrum and Lyapunov exponent from the output signal of the detectors in this paper．
2003,
15.
Abstract:
By using the Fourier series expansion, approximate analytical propagation equations of laser beams through a paraxial optical ABCD system with different apertures are derived. The hardedged aperture can be regarded as a special case treated here, while the other apertures can also be dealt with as a hardedged apterture. Numerical calculations show the advantage of our method and the consistency with the results by means of the Collins formula.
By using the Fourier series expansion, approximate analytical propagation equations of laser beams through a paraxial optical ABCD system with different apertures are derived. The hardedged aperture can be regarded as a special case treated here, while the other apertures can also be dealt with as a hardedged apterture. Numerical calculations show the advantage of our method and the consistency with the results by means of the Collins formula.
2003,
15.
Abstract:
The atmospheric attenuation properties of the HF and DF laser transmission. The absorption of watervapor in the atmosphere is very weak to the DF spectral lines, while those of the watervapor and CO2 are very strong to the HF spectral lines. The atmospheric attenuations of the HF and DF spectral lines are calculated based on the latest HITRAN 96 database and the meterologic data for different districts in China. For the selected HF spectral lines, the maximum absorption coefficient of watervapor in Hefei area is up to 10km-1, that of CO2 is up to 10-4 or 10-3km-1 and that of P2(8) line is the weakest. The maximum absorption coefficient of watervapor to DF spectral lines is 2 orders in the magnitude lower than that to HF spectral lines and attenuates drastically with the increase of
The atmospheric attenuation properties of the HF and DF laser transmission. The absorption of watervapor in the atmosphere is very weak to the DF spectral lines, while those of the watervapor and CO2 are very strong to the HF spectral lines. The atmospheric attenuations of the HF and DF spectral lines are calculated based on the latest HITRAN 96 database and the meterologic data for different districts in China. For the selected HF spectral lines, the maximum absorption coefficient of watervapor in Hefei area is up to 10km-1, that of CO2 is up to 10-4 or 10-3km-1 and that of P2(8) line is the weakest. The maximum absorption coefficient of watervapor to DF spectral lines is 2 orders in the magnitude lower than that to HF spectral lines and attenuates drastically with the increase of
2003,
15.
Abstract:
The large scale (ten/tens meters) quasiconcentric cavity used in high average output power farinfrared FEL and the shortpulse effects require that the numerical simulation must involve evolution in both space and time, which means huge quantity of calculating. To decrease quantity of calculating and keep accuracy, an new calculating method named "Heggens transform" was developed which is an integral expression similar to the KirchhoffFresnel expression and can be applied out of undulator．
The large scale (ten/tens meters) quasiconcentric cavity used in high average output power farinfrared FEL and the shortpulse effects require that the numerical simulation must involve evolution in both space and time, which means huge quantity of calculating. To decrease quantity of calculating and keep accuracy, an new calculating method named "Heggens transform" was developed which is an integral expression similar to the KirchhoffFresnel expression and can be applied out of undulator．
2003,
15.
Abstract:
The response of silicon p-n junction solar cell to DF laser irradiation is studied. It is found in the experiment that DF laser doesn't generate much photocarriers in the solar cell though the laser power is high enough to cause notable temperature rise. An approximate formula is deduced describing the temperature dependence of p-n junction leakage reverse current which is an important factor in the equation characterizing the output of the soar cell. With the equation, the photovoltaic effect and the temperature effect in the solar cell when laserirradiated are explained. Also with the formula, the output voltage of the solar cell under DF laser irradiation is calculated, which agrees with the experimental result．
The response of silicon p-n junction solar cell to DF laser irradiation is studied. It is found in the experiment that DF laser doesn't generate much photocarriers in the solar cell though the laser power is high enough to cause notable temperature rise. An approximate formula is deduced describing the temperature dependence of p-n junction leakage reverse current which is an important factor in the equation characterizing the output of the soar cell. With the equation, the photovoltaic effect and the temperature effect in the solar cell when laserirradiated are explained. Also with the formula, the output voltage of the solar cell under DF laser irradiation is calculated, which agrees with the experimental result．
2003,
15.
Abstract:
Peking University is planning to put up a FEL facility�PKU-FEL, which will be used as a tool for experimental studies on nonlinear transient physical process, chemical kinetics, molecular biology, material science, etc. Based on PKU-SCAF, a superconducting accelerator facility, PKU-FEL has the characteristics of high stability and high average power. Moreover, wavelength of PKU-FEL will cover the band from about 3 to 23μm and the pulse duration will be about 2ps. This paper gives a brief description of the design considerations．
Peking University is planning to put up a FEL facility�PKU-FEL, which will be used as a tool for experimental studies on nonlinear transient physical process, chemical kinetics, molecular biology, material science, etc. Based on PKU-SCAF, a superconducting accelerator facility, PKU-FEL has the characteristics of high stability and high average power. Moreover, wavelength of PKU-FEL will cover the band from about 3 to 23μm and the pulse duration will be about 2ps. This paper gives a brief description of the design considerations．
2003,
15.
Abstract:
According to characteristics of IR systems, the intensity distribution of an optical element in IR system is analyzed by optical gain. The optical element at focus plane is damageable element by laser. The damage mechanism of the detection and guidance functions of the IR system from the damage of optical element radiated by high power laser is presented. Based on the analysis on the spectrum responding characteristics analyzed by IR filter, detector and signal processing electrocircuit, the soft damage mechanism of resulted output signal disturbance in IR system radiated by low power laser, and the detection function disability in laser radiation time caused by laser are presented. The validate experiment of disability in IR system radiated by laser has been developed, the invalidation me
According to characteristics of IR systems, the intensity distribution of an optical element in IR system is analyzed by optical gain. The optical element at focus plane is damageable element by laser. The damage mechanism of the detection and guidance functions of the IR system from the damage of optical element radiated by high power laser is presented. Based on the analysis on the spectrum responding characteristics analyzed by IR filter, detector and signal processing electrocircuit, the soft damage mechanism of resulted output signal disturbance in IR system radiated by low power laser, and the detection function disability in laser radiation time caused by laser are presented. The validate experiment of disability in IR system radiated by laser has been developed, the invalidation me
2003,
15.
Abstract:
Capacitors are important storage components in pulsed power equipment. In order to reduce the volume of the power source equipment, the energy storage density of the capacitors must be increased. This paper describes the basic breakdown mechanism of capacitors. To avoid the disadvantage of film-foil type capacitors, the authors present two new techniques, which are metallized film structure and mixed-film structure. The energy density of two kinds of capacitors is over 500J/L．
Capacitors are important storage components in pulsed power equipment. In order to reduce the volume of the power source equipment, the energy storage density of the capacitors must be increased. This paper describes the basic breakdown mechanism of capacitors. To avoid the disadvantage of film-foil type capacitors, the authors present two new techniques, which are metallized film structure and mixed-film structure. The energy density of two kinds of capacitors is over 500J/L．
2003,
15.
Abstract:
Ti-50.6at.%Ni shape memory alloy specimens were irradiated under the austenite state (parent phase) using a tandem accelerator by 18MeV protons with doses of 1.53×1013and 1.53×1014H+/cm2. The microstructure and phase transformation of the specimens before and after irradiation were examined by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). After the irradiation the parent phase (austenite) was stabilized. R-phase transformation start temperature and the reverse martensitic transformation finish temperature decreased with the increasing proton fluence. They decreased about 13K and 6K at a dose of 1.53×1014H+/cm2, respectively. The reverse martensitic transformation start temperature and Rphase transformation finish temperature were not affected by t
Ti-50.6at.%Ni shape memory alloy specimens were irradiated under the austenite state (parent phase) using a tandem accelerator by 18MeV protons with doses of 1.53×1013and 1.53×1014H+/cm2. The microstructure and phase transformation of the specimens before and after irradiation were examined by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). After the irradiation the parent phase (austenite) was stabilized. R-phase transformation start temperature and the reverse martensitic transformation finish temperature decreased with the increasing proton fluence. They decreased about 13K and 6K at a dose of 1.53×1014H+/cm2, respectively. The reverse martensitic transformation start temperature and Rphase transformation finish temperature were not affected by t
2003,
15.
Abstract:
A high speed gated soft Xray multiframe image diagnostic system was developed for QiangGuangI generator, which was operated with a peak current of 1.5MA and a rise time of 80ns. In the system, a gated fourframe (3～5ns gate, 5～20ns separation) Xray camera, used in conjunction with a set of filtered pinholes was employed. Pinholes of 0.1mm and 0.3mm were used, which gave a spatial resolution of 0.56mm and 1mm, respectively. The pinholes were filtered with 2μm aluminized mylar. The system was sensitive to 150～300eV photons and to those greater than 550eV. Finally the last experimental results measured by this system in QiangGuangI generator were discussed.
A high speed gated soft Xray multiframe image diagnostic system was developed for QiangGuangI generator, which was operated with a peak current of 1.5MA and a rise time of 80ns. In the system, a gated fourframe (3～5ns gate, 5～20ns separation) Xray camera, used in conjunction with a set of filtered pinholes was employed. Pinholes of 0.1mm and 0.3mm were used, which gave a spatial resolution of 0.56mm and 1mm, respectively. The pinholes were filtered with 2μm aluminized mylar. The system was sensitive to 150～300eV photons and to those greater than 550eV. Finally the last experimental results measured by this system in QiangGuangI generator were discussed.
2003,
15.
Abstract:
The blowoff impulse of three different materials irradiated by soft Xray was studied on QiangguangI pulsed accelerator. The experimental results show that the coupling coefficients of blowoff impulse for grey paint, white paint and aluminum alloy irradiaded by Xray, the enegy of which was in the range from 0.20keV to 0.33keV and the average pulse width of which was 39ns, were in the range from 0.61Pa.s/(J·cm-2) to 0.80 Pa·s/(J·cm-2), from 0.58 Pa·s/(J·cm-2) to 0.97 Pa·s/(J·cm-2) and from 0.61 Pa·s/(J·cm-2) to 0.84 Pa·s/(J·cm-2), respectively, when Xray energy flux was in the range from 92J/cm2 to 136J/cm2, from 115J/cm2 to 159J/cm2 and from 163J/cm2 to 192J/cm2, respeclively.
The blowoff impulse of three different materials irradiated by soft Xray was studied on QiangguangI pulsed accelerator. The experimental results show that the coupling coefficients of blowoff impulse for grey paint, white paint and aluminum alloy irradiaded by Xray, the enegy of which was in the range from 0.20keV to 0.33keV and the average pulse width of which was 39ns, were in the range from 0.61Pa.s/(J·cm-2) to 0.80 Pa·s/(J·cm-2), from 0.58 Pa·s/(J·cm-2) to 0.97 Pa·s/(J·cm-2) and from 0.61 Pa·s/(J·cm-2) to 0.84 Pa·s/(J·cm-2), respectively, when Xray energy flux was in the range from 92J/cm2 to 136J/cm2, from 115J/cm2 to 159J/cm2 and from 163J/cm2 to 192J/cm2, respeclively.
2003,
15.
Abstract:
High spectral resolution transmission grating spectrometer is established by combining newly manufactured 2 000 l/mm transmission grating with a softＸray CCD. Transmission grating efficiencies have been studied experimentally and theoretically in order to obtain quantitative results of measured Ｘray spectra. Then, a method for unfolding the soft Ｘray spectrum measured with transmission grating spectrometer is introduced, in which the grating efficiencies, CCD quantum efficiencies and grating higher dispersive order overlapping have been taken into account. The developed quantitative measurement method has been applied to obtain Ｘray spectrum from laserentered gold cavity on “ShengguangⅡ” laser facility.
High spectral resolution transmission grating spectrometer is established by combining newly manufactured 2 000 l/mm transmission grating with a softＸray CCD. Transmission grating efficiencies have been studied experimentally and theoretically in order to obtain quantitative results of measured Ｘray spectra. Then, a method for unfolding the soft Ｘray spectrum measured with transmission grating spectrometer is introduced, in which the grating efficiencies, CCD quantum efficiencies and grating higher dispersive order overlapping have been taken into account. The developed quantitative measurement method has been applied to obtain Ｘray spectrum from laserentered gold cavity on “ShengguangⅡ” laser facility.
2003,
15.
Abstract:
The experimental investigation on non-equilibrium of Au plasmas irradiated directly by laser and heated by X-ray radiation was made in this paper. The physical mechanism was investigated and analyzed. Two kinds of targets, which were cone-disk and annulus-disk targets, were designed to study reemission ablated by Ｘ-ray radiation. The experimental results showed that cone-disk target could avoid the effects of plasma expansion from cone and laser scattered by cone on reemission from X-ray heated area, and emission spectrum from X-ray ablating disk is "pure and clear", but annulus-cone couldn't avoid effects of plasma and scattering laser．
The experimental investigation on non-equilibrium of Au plasmas irradiated directly by laser and heated by X-ray radiation was made in this paper. The physical mechanism was investigated and analyzed. Two kinds of targets, which were cone-disk and annulus-disk targets, were designed to study reemission ablated by Ｘ-ray radiation. The experimental results showed that cone-disk target could avoid the effects of plasma expansion from cone and laser scattered by cone on reemission from X-ray heated area, and emission spectrum from X-ray ablating disk is "pure and clear", but annulus-cone couldn't avoid effects of plasma and scattering laser．
2003,
15.
Abstract:
The fast Zpinch phenomenon and the physics of fast Zpinch are introduced in this paper. And the factors which influence the instability of fast Zpinch are simply analysed. The PSPICE circuit analyses are very useful for the design of the pulsed power. In the paper, the PSPICE circuit analyses is used for solving the thin annular shell of imploding wire array, and simultaneously with the pulsed power system. From the circuit analyses, some Zpinch physics parameters ( pinch time, velocity, radius, et al) are given simultaneously with the pulsed power ( current and voltage).
The fast Zpinch phenomenon and the physics of fast Zpinch are introduced in this paper. And the factors which influence the instability of fast Zpinch are simply analysed. The PSPICE circuit analyses are very useful for the design of the pulsed power. In the paper, the PSPICE circuit analyses is used for solving the thin annular shell of imploding wire array, and simultaneously with the pulsed power system. From the circuit analyses, some Zpinch physics parameters ( pinch time, velocity, radius, et al) are given simultaneously with the pulsed power ( current and voltage).
2003,
15.
Abstract:
The fluid equations and numerical algorithm are given to simulate twodimensional RayleighTaylor(RT) instability in cylindrical geometry in this paper. Simulation results agree well with the linear theory of RT instability. However the threshold at which nonlinear effects begin to become apparent in cylindrical geometry is clearly different from that in planar geometry and is related to the position of interface.
The fluid equations and numerical algorithm are given to simulate twodimensional RayleighTaylor(RT) instability in cylindrical geometry in this paper. Simulation results agree well with the linear theory of RT instability. However the threshold at which nonlinear effects begin to become apparent in cylindrical geometry is clearly different from that in planar geometry and is related to the position of interface.
2003,
15.
Abstract:
Effect of amplitude modulation and phase perturbation of incident fundamental field on the tripling efficiency and dynamic range has been discussed in details. The method which can improve the tripling efficiency and dynamic range has been proposed. Using type I/II angledetuning scheme for third harmonic generation, the parameter of harmonic conversion crystal has been optimized.
Effect of amplitude modulation and phase perturbation of incident fundamental field on the tripling efficiency and dynamic range has been discussed in details. The method which can improve the tripling efficiency and dynamic range has been proposed. Using type I/II angledetuning scheme for third harmonic generation, the parameter of harmonic conversion crystal has been optimized.
2003,
15.
Abstract:
The paper describes the numerical study on the vircator with stepped waveguide. Simulation results demonstrate that the length of stepped waveguide can strongly affect the microwave generation，when the resonance frequency of equivalent column cavity for stepped waveguide is about equal to the frequency of the virtual cathode oscillation, the efficiency of microwave generation is maximum and the spectrum of microwave is more singular, the efficiency of microwave generation varies periodically with the length of stepped waveguide.
The paper describes the numerical study on the vircator with stepped waveguide. Simulation results demonstrate that the length of stepped waveguide can strongly affect the microwave generation，when the resonance frequency of equivalent column cavity for stepped waveguide is about equal to the frequency of the virtual cathode oscillation, the efficiency of microwave generation is maximum and the spectrum of microwave is more singular, the efficiency of microwave generation varies periodically with the length of stepped waveguide.
2003,
15.
Abstract:
In order to essentially improve microwave output power and efficiency, a new idea about magnetically insulated transmission line oscillator (MILO) is brought forward, which use most of the load current to produce microwave. A new type of MILO that comprises traditional MILO and VCO, called MVO, is designed and simulated by 2D PIC method. The results show that both parts of MVO work well and the main frequency accords with slowwave structure (SWS), and that MVO yields an output power of 500MW higher than traditional MILO in the case of 25GW(at 500kV) inputpower with the efficiency enhanced from 6% to 8%.
In order to essentially improve microwave output power and efficiency, a new idea about magnetically insulated transmission line oscillator (MILO) is brought forward, which use most of the load current to produce microwave. A new type of MILO that comprises traditional MILO and VCO, called MVO, is designed and simulated by 2D PIC method. The results show that both parts of MVO work well and the main frequency accords with slowwave structure (SWS), and that MVO yields an output power of 500MW higher than traditional MILO in the case of 25GW(at 500kV) inputpower with the efficiency enhanced from 6% to 8%.
2003,
15.
Abstract:
A new type high efficiency Multiwave Cerenkov Generator is designed by employing a resonant cavity between the second slow wave structure and the output horn，and its physical process is analyzed by means of 2.5 PIC simulation. It is shown that, due to the decelerating gap mechanism and coupling cavity mechanism of the resonant cavity, its output power and efficiency increase as its longitudinal length reduces and its guiding magnetic field be lowered greatly. A typical simulation result is that, at the magnetic field of 0.63T, an Xband microwave with the average output power of 1.8GW and the peak power of 4GW is obtained with the input power of 5.8GW, and the average efficiency is over 30%.
A new type high efficiency Multiwave Cerenkov Generator is designed by employing a resonant cavity between the second slow wave structure and the output horn，and its physical process is analyzed by means of 2.5 PIC simulation. It is shown that, due to the decelerating gap mechanism and coupling cavity mechanism of the resonant cavity, its output power and efficiency increase as its longitudinal length reduces and its guiding magnetic field be lowered greatly. A typical simulation result is that, at the magnetic field of 0.63T, an Xband microwave with the average output power of 1.8GW and the peak power of 4GW is obtained with the input power of 5.8GW, and the average efficiency is over 30%.
