共查询到20条相似文献,搜索用时 15 毫秒
1.
T. Idehara V.N. Manuilov O. Watanabe M. Kamada La Agusu K. Yatsui W. Jiang 《International Journal of Infrared and Millimeter Waves》2004,25(1):3-14
In the article, results of numerical simulation of the gun with the cusp of magnetic field are presented. Short pulse version of the gun with explosion emission is investigated. Some preliminary analytical estimation of the beam and gun parameters are performed. Then, numerical optimization of the electrodes shape as well as magnetic field distribution is carried out. For preliminary separation of electrons and formation of the rectilinear beam, anode diaphragm is installed. After then, additional selection of electrons for decreasing the ripple is performed. For this purpose, channel walls are used for interception of some part of the electron beam. Reverse of the magnetic field in the diode part of the gun is formed. So, the formation of the rectilinear beam is combined with the region, where electrons obtain initial gyration energy. To prevent the disperse action of the own beam space charge forces, the system with big gradient of magnetic field (about 0.5-1 kGs/mm) is needed. According to results of the simulation, helical electron beam can be performed even at total compression ratio about 1000 and current density more than 50 kA/cm2. The designed electron gun provides acceptable performance for the large orbit gyrotron, such as operating current close to 300 A, the pitch-factor value about 1.5-1.7, deviation of the guiding centers from the axis (the ripple) /10 and /6 for operation on 3-rd and 5-th cyclotron harmonic correspondingly (wavelength =0.5 and 0.3 mm) and velocity spread within the range 10-15%. 相似文献
2.
Sh.E. Tsimring 《International Journal of Infrared and Millimeter Waves》2001,22(10):1433-1468
The stability of the electron beams and maximum share of the electrons oscillatory energy, i.e. finally efficiency, power, and pulse duration of the gyrotron to a considerable extent depend on the velocity and the energy spread (VESP) of the HEB. The basic factors determining VESP in the helical beams are discussed. Among these factors static (initial velocities, cathode heterogeneities, space charge fields) and dynamic (negative mass and diochotron instabilities and a global instability connected with the capture of the electrons in the gyrotron adiabatic trap) factors are considered. Qualitative models of the excitation of the space charge oscillation as well the parasite electromagnetic radiation of the HEB are developed. Some experimental data of the investigation of the parasitic electromagnetic radiation spectrum in one gyrotron are discussed. The methods of the experimental investigation of the VESP are described. 相似文献
3.
S. Sabchevski T. Idehara I. Ogawa M. Glyavin K. Ohashi 《International Journal of Infrared and Millimeter Waves》2002,23(5):675-692
A computer code for simulation of beam-field interaction in a resonant cavity of a gyrotron has been developed. It is based on a self-consistent, time-independent, single-mode physical model. The code has been applied to the analysis of the electrodynamical system of a novel high-harmonic gyrotron with axis-encircling beam and a permanent magnet. In this paper both the physical model and numerical techniques used are outlined. Some results of the numerical experiments are presented and discussed. 相似文献
4.
V. N. Manuilov T. Idehara M. Yu. Glyavin Information not available LaAgusu M. Kamada T. Kanemaki Wiehua Jiang K. Yatsui 《International Journal of Infrared and Millimeter Waves》2005,26(1):15-28
Short-pulse powerful Large Orbit Gyrotron with total electron energy about 400 kV and beam power in the cavity up to 100 MW is now under developing at FIR FU. Suitable for 200 ns pulse duration electron-optic system is analyzed. Results of numerical simulation for explosion emission cusp-type electron guns and magnetic field intensity about 8 T are presented. Sensitivity of the guns to small deviations from the nominal operating regime is investigated. Some versions of the gun with different accelerating potential as well as different beam current passing through the cavity (60-300A) are suggested. Current reduction simplifies the problems of mode competition and potential depression in the cavity, but at the same time decrease output power. To diminish current special diaphragms are suggested. Results of numerical simulation of collector corresponding to each version of the gun design including power density distributions along its surface are presented. It is shown that beam quality and collector regimes are suitable for LOG operation. 相似文献
5.
T. Idehara Y. Iwata I. Ogawa 《International Journal of Infrared and Millimeter Waves》2003,24(2):119-128
Frequency down-shift in the initial stage of CW or long pulse operation of a submillimeter wave gyrotron, Gyrotron FU IV, is observed. The shift occurs in a few minutes after turning on the operation and the amount of the shift attains even 0.1 GHz. The observation results are analyzed on the basis of a simple model for heat conduction in the region of a resonant cavity. The frequency shift is explained consistently by expansion of the cavity. 相似文献
6.
Shi-Chang Zhang 《International Journal of Infrared and Millimeter Waves》2001,22(4):571-576
A gyrokinetic analysis is presented to the influence of the electron beam eccentricity on the power and starting current of a coaxial cavity gyrotron, which operates in a higher-order mode TE31, 17, 1 with a frequency of 165 GHz. It is found that the starting current becomes larger because of the existence of the electron-beam eccentricity. Especially, the power will be decreased substantially by the electron beam eccentricity, for example, down to 93% of the power without any eccentricity even if the eccentricity is 1% of the outer conductor radius. The acceptable range of the electron beam voltage and operating magnetic field for the establishment of the electromagnetic oscillation is narrowed by the electron-beam eccentricity. 相似文献
7.
M. A. Moiseev V. E. Zapevalov N. A. Zavolsky 《International Journal of Infrared and Millimeter Waves》2001,22(6):813-833
The possibilities to increase efficiency of relativistic gyrotrons by optimizing gyrotron parameters have been considered and different calculated models of gyrotrons, compared. Dependencies of the efficiency and optimal parameters on the accelerating voltage have been obtained. It is shown that efficiency of 35-45% can be achieved in a strongly relativistic gyrotron without energy recovery, and 60-70%, in the device with single stage energy recovery of the electron beam. 相似文献
8.
S. N. Spark A. W. Cross A. D. R. Phelps 《International Journal of Infrared and Millimeter Waves》1992,13(5):625-646
The replacement of conventional pulsed magnetic field coils previously used to generate the intra-cavity B-field with an 11T superconducting magnet is reported. The resulting more stable mm-wave output pulse is shown and the refurbishment requirements of both the field emission, field-immersed, cold cathode and Marx bank spark gaps demonstrated. This system proved to be tunable, oscillating from 20GHz up to 110GHz, with peak power levels of 450kW and 300kW respectively. Other operating parameters were also examined including mm-wave pulse length as a function of anode-cathode position. The pulse length increased from 87±6ns to 310±10ns with a 2.5 cm horizontal transit of the cathode away from the anode. A similar effect was witnessed with the increase of the intra-cavity B-field from 1.00T to 5.00T resulting in the mm-wave pulse duration increasing from 250±40ns. Second harmonic operation of the cavity resulted in 0.5kW of radiation observed at 96GHz. The pulse-to-pulse mm-wave stability coupled with the mode selectivity of the ohmic-Q-dominated cavity resulted in the identification of several oscillating modes including the TE12, cut-off frequency 21.1 GHz, the TE02, cut-off frequency 29.1 GHz, the TE35 at 74 GHz and the TE14,2, at 88GHz. 相似文献
9.
A nonlinear numerical simulation of a second harmonic gyrotron oscillator is presented in this paper. Mode competition from a competing fundamental mode is investigated. In addition, a self-consistent nonlinear theoretical model, including the effect of velocity spread, is applied to analyze the second harmonic gyrotron. A series of numerical calculations is carried out for different electron beam parameters. The results are compared with that of calculations using the cold-cavity, fixed field approximation and with experiments. Good agreement is found between our calculations and an experiment at Fukui University. The azimuthal polarization of the field and the choice of the electron beam radius are also discussed. 相似文献
10.
N. Sato H. Shimawaki K. Yokoo J. Sakuraba Y. Yamada K. Watanabe 《International Journal of Infrared and Millimeter Waves》1999,20(6):979-989
A liquid helium free superconducting magnet was designed and fabricated and for an application to a millimeter wave gyrotron and a peniotron. The magnet generates a magnetic field of 5T in a 100mm room temperature bore and has been continuously working for more than 5,400 hours without troubles.The magnet system was applied to the millimeter wave gyrotron experiments to confirm the stability of the magnet. In the experiments, stable operations of the gyrotron were achieved in the frequency range of 30 - 133GHz. 相似文献
11.
M. Yu. Glyavin V. E. Zapevalov 《International Journal of Infrared and Millimeter Waves》1998,19(11):1499-1511
Influence of some types of reflections on oscillatory processes in gyrotrons has been studied. Estimations of the conditions for oscillation stability in the presence of a reflected signal are given. The processes in a gyrotron with a fixed structure of the RF field have been modeled numerically, and enhancement of the spectrum signal in the presence of reflections has been studied. 相似文献
12.
M. Glyavin V. Zapevalov T. Idehara I. Ogawa 《International Journal of Infrared and Millimeter Waves》2003,24(4):409-418
Influence of power supply voltage instability on gyrotron operation regime is investigated. Dependence of efficiency versus variations of external parameters is given and conditions of oscillations cutoff are determined. It is shown that positive voltage fluctuations result in sharp falling efficiency and failure of self-oscillations and the steadiest gyrotrons are those with short cavities and the large ratio of transverse electron speed to longitudinal one around 1.5 - 2. Comparison of theoretical and experimental results is given. 相似文献
13.
V. L. Bratman A. E. Fedotov T. Idehara 《International Journal of Infrared and Millimeter Waves》2001,22(10):1409-1420
Competition of the operating modes at the second cyclotron harmonic with spurious modes at fundamental is studied numerically for the cases of gyrotron and traveling opposite spurious modes in the gyrotron FU II. This competition limits significantly the output power at the second harmonic. The results are in good agreement with experiments. 相似文献
14.
I. Ogawa Y. Miyake T. Idehara S. Sabchevski 《International Journal of Infrared and Millimeter Waves》2002,23(1):1-19
A novel focusing mirror based on the shifting of the beam phase according to the Gaussian beam optics enabled us to realize a focusing elements with different focal lengths in different directions and to convert the gyrotron output into a Gaussian-like beam. In this paper, we compare the quality of beams produced by the new system (which includes novel mirrors) and a conventional system consisting of a quasi-optical antenna, an ellipsoidal mirror and two parabolic cylinder mirrors. 相似文献
15.
V. Zapevalov T. Idehara S. Sabchevski K. Ohashi V. Manuilov M. Glyavin S. Kornishin A. Kuftin V. Lygin O. Malygin M. Moiseev A. Pavel''ev V. Tzalolikhin N. Zavolsky H. Kobayashi T. Yokoyama I. Ogawa S. Mitsudo T. Kanemaki Y. Iwata H. Hoshizuki 《International Journal of Infrared and Millimeter Waves》2003,24(3):253-260
The paper presents results of numerical analysis and outlines the computer-aided design of a novel high-harmonic gyrotron with a beam of electrons gyrating along axis-encircling trajectories. The electron beam is formed by a novel electron-optical system (EOS) based on an electron gun of diode type with thermionic cathode and gradual reversal of the magnetic field. The results of numerical simulations predict satisfactory performance of the EOS and appropriate beam quality parameters. The tube design allows one to install different cavities optimized for excitation of TE4,1 mode at the fourth harmonic of the cyclotron frequency or TE3,1 mode at the third one. The target parameters of the device are: frequency about 112 GHz; output power near 1 kW and efficiency of several percent. 相似文献
16.
G. F. Brand 《International Journal of Infrared and Millimeter Waves》1984,5(6):839-851
The output power levels of Gyrotron II are very much higher than those predicted when one assumes that a single waveguide mode exists throughout the cavity and output section. In this paper we demonstrate the importance of mode conversion at the point where the uniform waveguide meets the first down-taper.The method of calculating the mode conversion used here is superior to many that appear in the literature. It uses the correct boundary conditions, it treats the wave magnetic field fully and, especially important in relation to cavities, it is applicable to waveguide modes near cutoff. 相似文献
17.
Yang Yan HongFu Li Shenggang Liu 《International Journal of Infrared and Millimeter Waves》1999,20(4):525-532
The self-consistent nonlinear theory is employed to analyze the inner-slotted high harmonic gyrotron, it is found that the structure of advantiageus to the interactin, the efficiency of interaction is above 30%. 相似文献
18.
P.-K. Liu E. Borie M. V. Kartikeyan 《International Journal of Infrared and Millimeter Waves》2000,21(12):1917-1943
The preliminary design of a moderate (25-50 kW) gyrotron operating at the ISM (industrial, scientific, medical) frequency of 24.1 GHz is presented. Operation at the second harmonic is considered so that one can obtain radiation at the given frequency with only half the magnetic field required. 相似文献
19.
A self-consistent particle simulation code has been developed for the research of a 35-GHz third-harmonic Low-voltage complex cavity gyrotron. Aided with microcomputer we use FORTRAN to simulate the process of interaction between electron beam and electromagnetic field. About 7000 macro particles are included at the same time. In the program many useful physical graphs are accessible for the further research of this kind of gyrotron such as the field profile, electrons distribution in various spaces, output power, efficiency and et al. Such simulation results may be helpful to the optimization of devices operation parameters 相似文献
20.
A. A. Bogdashov A. V. Chirkov G. G. Denisov A. N. Kuftin Yu. V. Rodin E. A. Soluyanova V. E. Zapevalov 《International Journal of Infrared and Millimeter Waves》2005,26(6):771-785
A high-efficiency mode converter of the ITER gyrotron operating mode into the Gaussian wave beam has been developed. It includes an irradiating waveguide with shallow deformation and profiled quasi-optical mirrors to increase the Gaussian content. Low-power tests were carried out with a TE25.10 mode exciter and a mode converter. A prototype of the short-pulsed 170 GHz gymtmn with the new converter was manufactured and tested. Diffraction losses measured inside the tube were less then 2% at the 1 MW power level. A high Gaussian mode content in the output beam has been also demonstrated. 相似文献