共查询到20条相似文献,搜索用时 46 毫秒
1.
Nusinovich G.S. Read M.E. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1999,27(2):355-362
The scaling of operating parameters and the tendencies in the efficiency of the step-tunable gyrotron operating in a set of modes in a cavity of a given length are considered. Results of calculations are reported for the design of a ~1-kW, step-tunable gyrotron oscillator operating from 150 to 600 GHz in steps of about 15 GHz. Detailed results are presented for the efficiency, power losses in the cavity, and the starting conditions. Designs of the electron gun electrodes and of an output mode transducer are also presented. Full modulation of the radiation via the modulating anode of a magnetron injection gun is considered. The gyrotron would be of use for plasma diagnostics and spectroscopy, including electron paramagnetic resonance spectroscopy (EPR) 相似文献
2.
E. Borie 《International Journal of Infrared and Millimeter Waves》2003,24(4):419-427
The modulation of the output power of a 140 GHz gyrotron for fusion plasma heating at the W7-X Stellarator is simulated numerically. It is shown that for appropriate beam properties, power modulation is possible. The output power shows almost no dependence on whether the accelerating voltage is being increased or decreased. 相似文献
3.
The problem of calculating the noise factor of a traveling-wave gyrotron is solved for a model of a thin annular multistart-helical
electron flux taking into account the effect of the quasistatic space-charge field. Plots of the gain and the noise factor
of the traveling-wave gyrotron versus the electrical parameters of the amplifier are obtained.
Zh. Tekh. Fiz. 68, 130–132 (February 1998) 相似文献
4.
Dumbrajs O. Nuisnovich G.S. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(4):452-457
A theory is presented which describes the dependence of the multimode operation of a gyrotron on the modulation and beam voltages. Nonlinear nonstationary processes are considered. An approximate start-up scenario of a gyrotron is determined which makes it possible to achieve single-mode excitation and high-efficiency operation in a desired mode, as well as to switch the tube to a similar operation in other modes 相似文献
5.
T. Idehara Y. Shimizu S. Makino K. Ichikawa T. Tatsukawa I. Ogawa G. F. Brand 《International Journal of Infrared and Millimeter Waves》1997,18(2):391-403
Amplitude modulation of gyrotron by a small modulation of the anode voltage is calculated using an energy transfer formula.
Experimental measurements using a submillimeter wave gyrotron are in good agreement. One hundred percent modulation of the
output at frequencies up to several hundred kilohertz has been achieved with anode modulation levels of only a few percent.
Numerical calculations lend further support to the experimental results. 相似文献
6.
Pereyaslavets M. Idehara T. Nishida N. Yoshida K. Ogawa I. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1999,27(2):363-367
Frequency modulation of the gyrotron output has been numerically simulated employing the approximation of weakly relativistic, mono-velocity electron beam as well as a quasi-empirical approach. The simulation results are compared to a first experiment in the 300 GHz region performed with a submillimeter-wave gyrotron named “Gyrotron FU IV”. The modulation amplitude of 30 MHz has been achieved by a 120 V modulation of the accelerating voltage resulting in the variation of the relativistic electron mass and in the corresponding modulation of the electron cyclotron frequency. Calculated amplitudes of frequency modulation are in reasonable agreement with the experimental results 相似文献
7.
Gilgenbach R.M. Hochman J.M. Jaynes R.L. Cohen W.E. Rintamaki J.I. Peters C.W. Vollers D.E. Lau Y.Y. Spencer T.A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(3):282-289
Microwave pulse shortening experiments have been performed on a rectangular-cross-section (RCS) gyrotron driven by the Michigan Electron Long Beam Accelerator (MELBA) at parameters V=-800 kV, Itube=0.3 kA and pulselengths of 0.5-1 μs. Pulse shortening typically limits the highest (10 MW level) microwave power pulselength to 100-200 ns. Potential explanations of pulse shortening are being investigated, particularly plasma production inside the cavity and at the e-beam-collector. We report the first optical spectroscopy diagnostic measurements inside an operating gyrotron as a means of exploring plasma effects on pulse shortening. Plasma hydrogen H-α line radiation has been characterized in both time-integrated and temporally-resolved measurements and correlated with microwave power/cutoff. Hydrogen is believed to originate from water absorbed on internal tube surfaces in the gyrotron 相似文献
8.
S. Lütgert 《International Journal of Infrared and Millimeter Waves》1993,14(2):239-249
For the use of oscillators in microwave networks, the knowledge of the behavior of the isolated oscillator is not sufficient. Of major interest is the interaction of the device with the external circuit, where questions about stability, modulation, injection locking, noise, etc. arise. If it is possible to describe the behavior of the active element in the frequency domain, the answers to the above mentioned questions can be found utilizing the standard methods of network theory. Recently the gyrotron oscillator has been described successfully in the frequency domain [1]. 相似文献
9.
A. Fernández N. Kharchev A. Pshenichnikov Yu. Bondar K. Sarksyan A. Tolkachev M. Petelin 《International Journal of Infrared and Millimeter Waves》2007,28(9):705-711
An experiment performed with the gyrotrons of the TJ-II ECRH system has been performed to influence the gyrotron output radiation
with a relatively weak wave returned from an external mechanically modulated reflector. An original method is proposed for
directly measuring the wavelength of electromagnetic radiation in the free space. The method has been demonstrated in measurements
of the wavelength of a high-power gyrotron radiation in the millimeter wavelength range used for plasma ECR heating in the
TJ-II stellarator. 相似文献
10.
Manheimer W.M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2001,29(4):639-648
Theoretical estimates of electron cyclotron shot noise in gyroklystrons have recently been confirmed at low currents. However at high beam current, the noise temperature is always reduced. We examine the effect of transverse collective effects on the shot noise. There are two collective effects; shielding, which reduces the noise; and instability, which increases it. It is shown that the effect of transverse shielding is negligible unless the gyrotron beam is extremely cold. Regarding instability, if the bare shot noise amplitude is denoted Ξ, then the shot noise, including the effect of instability, can be expressed as Ξ(1+A exp Γ), where Γ is the integrated growth. The effect of instability is then measured by two parameters, Γ and A. For a cold gyrotron beam, A is about 0.3, meaning about 10 dB of power growth is needed for the instability to manifest itself. Thermal effects both reduce A and Γ. For realistic gyrotron beams, about 20-25 dB of power e folds would be necessary for instability to manifest itself. To summarize, the theory developed explains the absence of instability in the measurements, but indicates that phenomena other than transverse shielding are responsible for the noise reduction 相似文献
11.
V. A. Flyagin V. I. Khizhnyak V. N. Manuilov M. A. Moiseev A. B. Pavelyev V. E. Zapevalov N. A. Zavolsky 《International Journal of Infrared and Millimeter Waves》2003,24(1):1-17
Main results of experimental testing of the 140 GHz/1.5 MW coaxial gyrotron are summarized. High selective properties of the coaxial cavities and a possibility to increase considerably the efficiency of a coaxial gyrotron only by applying independently an appropriate voltage on its electrodes (without any design modification) have been confirmed. Successful uses of the two-potential connection scheme for the frequency step tuning and output power modulation in a coaxial gyrotron has been also demonstrated. 相似文献
12.
V. E. Zapevalov A. B. Pavelyev V. I. Khizhnyak 《Radiophysics and Quantum Electronics》2000,43(8):671-674
It is shown that the efficiency of a coaxial gyrotron can be increased considerably by applying only independently appropriate voltages to its electrodes (without modifying design). The proposed scheme is also suitable for stepwise frequency tuning and for deep modulation of output power. 相似文献
13.
O. Dumbrajs 《International Journal of Infrared and Millimeter Waves》1990,11(1):61-67
A self—consistent calculation of the self—modulation instability in gyrotrons operating in whispering gallery modes is carried out in the cold cavity approximation for satellite modes. The approach is illustrated numerically in the case of the planned operation of the KfK gyrotron in the TE10,4 mode. 相似文献
14.
High-frequency gyrotron operation in the TE611 whispering gallery mode is reported. Powers as high as 112 kW and an efficiency as high as 25.4 percent have been obtained. In addition to the TE611 mode, ten other fundamental modes with frequencies between 133.9 and 216.4 GHz were observed. A quasi-optical antenna for whispering gallery modes has been tested for the TE611 mode. The combination of this antenna and a reflector produces a well-collimated linearly polarized RF beam suitable for electron cyclotron resonance heating (ECRH) or plasma diagnostics. The experimental conversion efficiency was determined to be 89 percent, and the cross polarization was down by 25 dB. A new quasi-optical transmission line employing this antenna has also been tested with the gyrotron. The absence of mode competition for the TE611 mode, as well as the efficient conversion of the output radiation into a linearly polarized Gaussian-like beam, substantiates the arguments for operation in surface modes in high-power gyrotrons. The implications of quasi-optical antennas for megawatt gyrotron window design are discussed. 相似文献
15.
A method for measurement of gyrotron amplitude noise using the Mach-Zehnder interferometer as a rejection filter, the measurement
facility, and results of testing a 140-GHz industrial high-power gyrotron are discussed. The method improved the sensitivity
by two orders of magnitude over that of the direct detection method. The experimental relative power spectral density in a
frequency range of 50–250 MHz from the line center is 7 × 10−20–5 × 10−19 1/Hz. 相似文献
16.
N. N. Skvortsova D. V. Malakhov V. D. Stepakhin S. A. Maiorov G. M. Batanov V. D. Borozosekov E. M. Konchekov L. V. Kolik A. A. Letunov E. A. Obraztsova A. E. Petrov D. O. Pozdnyakov K. A. Sarksyan A. A. Sorokin G. V. Ukryukov N. K. Kharchev 《JETP Letters》2017,106(4):262-267
A dusty plasma formed in chain exothermal reactions initiated by radiation of a high-power gyrotron in mixtures of metal and dielectric powders has been described. An oscillatory character of such chain reactions, as well as the appearance of dust particles at the first (explosive) stage, has been detected. The tracks, velocities, and sizes of dust particles have been measured. It has been revealed that ensembles of dust particles appear in a reactor after switching-off of the gyrotron against the background of development of chemical reactions. The time of existence of these ensembles is three or four orders of magnitude larger than the duration of a microwave radiation pulse. The quasistationary state of the low-temperature plasma with charged macroparticles appears because of both the chemical heating of the mixture in the reactor and thermophoresis. It has been shown that dust particles are necessary as crystallization nuclei for the creation (or deposition) of complex composites of nano- and micromaterials produced in secondary plasma chemical synthesis. 相似文献
17.
V. E. Zapevalov V. K. Lygin O. V. Malygin M. A. Moiseev V. I. Khizhnyak V. P. Karpov E. M. Tai T. Idehara S. Mitsudo I. Ogawa T. Saito 《Radiophysics and Quantum Electronics》2007,50(6):420-428
We consider a general concept of construction, the possible versions, and specific features of a gyrotron, whose output power
in CW oscillation regime can reach a few kilowatts at a frequency of 300 GHz. The gyrotron is designed for work in a high-frequency
facility in combination with a “dry” cryomagnet, which ensures a magnetic field of up to 12 T, required for the gyrotron operation.
The basic results of numerical simulation and optimization of the electron gun, the resonant cavity, and other subsystems
of the gyrotron are presented. The designs used for the gyrotron development are justified. Preliminary experiments showed
the efficiency of the pilotproduction gyrotron with an output power of about 2 kW, which is record-breaking in this frequency
range.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 6, pp. 461–470, June 2007. 相似文献
18.
A. V. Sidorov V. G. Zorin I. V. Izotov S. V. Razin V. A. Skalyga 《Technical Physics》2010,55(10):1540-1542
Experimental data for generating intense beams of multiply charged heavy gas ions are reported. The beams are extracted from
the dense plasma of an ECR discharge with quasi-gasdynamic confinement provided by the powerful microwave radiation of a gyrotron
in a magnetic trap. The axisymmetric magnetic trap makes it possible to extract uniform (in transverse coordinates) plasma
fluxes from it, and the use of a multiple-aperture extraction system makes it possible to increase the beam current by more
than an order of magnitude compared with the ECP sources currently available. Multiply charged nitrogen ion beams with a current
of 150 mA and a normalized emittance of 0.9π mm mrad are obtained. 相似文献
19.
N. A. Zavol’skii V. E. Zapevalov M. A. Moiseev L. L. Nemirovskaya 《Radiophysics and Quantum Electronics》1997,40(6):523-529
We study two versions of a gyrotron operating in the TE28.7 and TE31.8 modes for electron-cyclotron heating of plasma in the international thermonuclear reactor ITER. The gyrotron cavity parameters
are optimized allowing for ohmic losses, dips in electron beam potential, and velocity spread. The influence of the ion compensation
for the space charge, the setting of oscillations at when the gyrotron is switched on, and the competition between the operating
and parasitic modes are discussed. The possibility of attaining an efficiency of 32 to 36% for a specific power of ohmic losses
in the cavity of less than 2.5 kW/cm2 in the TE28.7 mode and 2 kW/cm2 in the TE31.8 mode is demonstrated.
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh
Zavedenii, Radiofizika, Vol. 40, No. 6, pp. 788–797, June, 1997. 相似文献
20.
O. Dumbrajs 《International Journal of Infrared and Millimeter Waves》1997,18(11):2111-2115
Gyrotrons are regarded as a necessary component of any modern fusion machine. They are presently used primarily to heat the
electron component of the plasma. However, gyrotrons can be utilized also to drive the current, to stabilize MHD modes, to
measure the ion temperature by means of the collective Thomson scattering, to mention just a view plasma diagnostic purposes.
In this work we present a design of a multifrequency gyrotron, i.e., a gyrotron which generates RF power simultaneously at
several frequencies and discuss possible applications of such tubes. 相似文献