共查询到20条相似文献,搜索用时 15 毫秒
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T. Idehara I. Ogawa La Agusu T. Kanemaki S. Mitsudo T. Saito T. Fujiwara H. Takahashi 《International Journal of Infrared and Millimeter Waves》2007,28(6):433-442
Gyrotron FU CW II with an 8 T liquid He free superconducting magnet, the second gyrotron of the THz Gyrotron FU CW Series,
has been constructed and the operation test was successfully carried out. It will be used for enhancing the sensitivity of
600 MHz proton-NMR by use of Dynamic Nuclear Polarization (DNP). The designed operation mode of the gyrotron is TE2,6 at the second harmonic. The corresponding frequency is 394.6 GHz. The real operation frequency is 394.3 GHz at TE06 mode, because of fabrication error of the diameter of the cavity. The operation is in complete CW at the output power of
around 30 W or higher at the TE06 cavity mode. There are many other operation modes at the fundamental and the second harmonic. Typical output power of the
fundamental and the second harmonic are higher than 100 W and 20 W, respectively. The highest frequency observed up to the
present is 443.5 GHz at the second harmonic operation of TE6,5 mode. The measured results are compared with the theoretical consideration. 相似文献
3.
La Agusu T. Idehara I. Ogawa T. Saito T. Kanemaki H. Takahashi T. Fujiwara 《International Journal of Infrared and Millimeter Waves》2007,28(7):499-511
A CW gyrotron for the sensitivity enhancement of NMR spectroscopy through dynamic nuclear polarization has been designed.
The gyrotron operates at the second harmonic and frequency of 394.6 GHz with the main operating mode TE0,6. Operating conditions of other neighboring cavity modes such as TE2,6 at frequency of 392.6 GHz and TE2,3 at frequency of 200.7 GHz were also considered. The experimental conditions of the gyrotron at low and high voltages are
simulated. The output power of 56 watts corresponds to the efficiency of 2 percent at low voltage operation and frequency
of 394.6 GHz is expected. 相似文献
4.
O. Dumbrajs H. Wenzelburger 《International Journal of Infrared and Millimeter Waves》1988,9(12):1067-1086
Expected efficiencies for the possible operation of the KfK gyrotron at the first, second and third harmonics are estimated. The results obtained in the cold cavity approximation and in self-consistent calculations are compared. Mode competition between the modes operating at the fundamental and at the second harmonic is investigated. Regions of stable single-mode generation are established. Effect of the the magnetic field tapering on the mode competition is illustrated. 相似文献
5.
La Agusu T. Idehara H. Mori T. Saito I. Ogawa S. Mitsudo 《International Journal of Infrared and Millimeter Waves》2007,28(5):315-328
Design of a CW 1 THz gyrotron at second harmonic operation using a 20 T superconducting magnet has been described. The mode
competition analysis is employed to investigate operation conditions of second harmonic mode, which is being excited at the
frequency ranging from 920 GHz to 1014 GHz. The output power up to 250 watt corresponding to the efficiency of 4.16 percent
could be achieved by using an electron beam with accelerating voltage 30 kV and current 200 mA. The important advantage of
this gyrotron is that the single mode excitation at second harmonic, and extremely high frequency of the radiation, could
be maintained even at high currents. It opens possibility to realize a high power radiation source at 1 THz. Such gyrotron
is under construction at FIR Center, University of Fukui. 相似文献
6.
N. P. Venediktov V. V. Dubrov V. E. Zapevalov S. Yu. Kornishin A. V. Kotov A. N. Kuftin O. V. Malygin A. S. Sedov A. Sh. Fiks V. I. Tsalolikhin 《Radiophysics and Quantum Electronics》2010,53(4):237-243
We present the results of the experiments on a continuous-wave gyrotron with an output frequency of about 260 GHz, which has
been developed for dynamic polarization of nuclei and is operated at the second cyclotron-frequency harmonic. For an accelerating
voltage of 16 kV and a beam current of 0.3 A, a maximum continuous-wave radiation power of about 200 W has been obtained.
Measurements of the thermal load on the resonator cavity allow evaluating its actual ohmic Q-factor. Gyrotron radiation is
also observed at other frequencies and modes. Their generation zones and the structure of the output radiation have been studied.
Long-term stability of gyrotron parameters has been determined. 相似文献
7.
O. Dumbrajs M. Thumm J. Pretterebner D. Wagner 《International Journal of Infrared and Millimeter Waves》1992,13(6):825-840
Mode conversion at discontinuities of an ordinary gyrotron cavity is examined. It is shown how the production of unwanted spurious modes can be reduced substantially by introducing smooth transition regions between the individual parts of the cavity. The cavity of the 140 GHz KfK gyrotron operating in the TE10,4 mode is used as an example. Cavity and adjacent tapered output waveguide are optimized as a single unit. 相似文献
8.
M. V. Kartikeyan E. Borie M. Thumm 《International Journal of Infrared and Millimeter Waves》2007,28(8):611-619
A design concept of a 250 GHz, ≈ 50 W, CW, second harmonic gyrotron for spectroscopy will be presented in this paper. Mode
competition, in particular with regard to competition with first harmonic modes, and mode selection procedures are carefully
investigated by considering various candidate modes and the TE6,2 and TE6,3 modes are chosen as probable operating modes. Cold cavity and self-consistent calculations of power and efficiency are carried
out to determine optimum parameters for these two modes. The results indicate that an output power of well over 50 W, CW can
be achieved. 相似文献
9.
Hezhong Guo Hoppe D.J. Rodgers J. Perez R.M. Tate J.P. Conroy B.L. Granatstein V.L. Bhanji A.M. Latham P.E. Nusinovich G.S. Naiman L. Shiaw-Huei Chen 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(5):822-832
Phase-locking in a 34.5-GHz special complex cavity gyrotron oscillator operating at the second harmonic of the electron cyclotron frequency was studied. Injection of the locking power was made via a quasi-optical circulator connected to the gyrotron output. Locking bandwidth was measured by comparing the phase of the injection signal and output signal using a balanced mixer. Locking was observed with input power level as low as 40 dB below the gyrotron output power. The locking bandwidth is, however, narrower than in gyrotrons operating at the fundamental cyclotron frequency which may be attributed to the longer resonant cavity in the second harmonic gyrotron and the corresponding larger value of external quality factor. The measurements are roughly in agreement with predictions of Adler's phase-locking equation which is given for our system in terms of powers propagating in the output waveguide toward and away from the gyrotron cavity 相似文献
10.
Spectral domain analysis, scattering matrix analysis and PIC simulations are used here to design a second harmonic gyrotron cavity with an internal blazed grating which favors operation at the second harmonic of the electron cyclotron frequency rather than operation at the electron cyclotron frequency itself. Based on these simulations, the cavity design is optimized. The results show that a new gyrotron with higher power and higher frequency can be achieved by incorporating such a blazed grating. 相似文献
11.
V. L. Bratman Yu. K. Kalynov V. N. Manuilov 《Radiophysics and Quantum Electronics》2009,52(7):472-481
We review briefly the main ideas and achievements in the field of physics related to shortwavelength large-orbit gyrotrons,
in which the coupling of electrons with the working mode and the discrimination of parasitic modes in the case of resonance
at the high cyclotron harmonic are more efficient compared with conventional gyrotrons. The results of studying a new large-orbit
gyrotron with moderate electron energies of 50–80 keV and comparatively low magnetic fields of 10.5–14 T are presented. In
this gyrotron, high-power single-mode generation was obtained at the second and third cyclotron harmonics in the frequency
range 0.55–1.00 THz. The prospects of development and application of short-wavelength large-orbit gyrotrons are discussed. 相似文献
12.
G. G. Denisov N. I. Zaitsev S. V. Kuzikov M. E. Plotkin 《Radiophysics and Quantum Electronics》2008,51(10):756-767
Mode selection is a key problem from the viewpoint of maintaining the single-mode generation regime in high-power gyrotrons
operated at axisymmetric modes. In this paper, we propose several electrodynamic methods of mode selection, which allow separating
the electrically strong axisymmetric higher-order mode from spurious modes. The possibility of suppressing the nearest spurious
modes efficiently, by using either wide slits in the cavity, or azimuthal corrugations on the walls of the tapered cavity,
is shown. A method of mode selection at cyclotron frequency harmonics is proposed. The results of studying two types of gyrotron
cavities experimentally at a low power level confirmed their high selective properties. The cavities were calculated aiming
at using them as the basis for creation of a gyrotron operated at the TE0.3 mode and producing a power of 5–10 MW in 1 μs
long pulses at a wavelength of 1 cm.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 10, pp. 837–849, October 2008. 相似文献
13.
准光共焦波导具有功率容量大、模式密度低的特点,能够有效地减少模式竞争对回旋管互作用的影响,有利于高次谐波太赫兹回旋管的设计.为提高太赫兹准光回旋管的互作用效率,在共焦柱面波导的基础上,研究了一种新型高频互作用结构——双共焦波导结构,设计了一种330 GHz二次谐波双共焦结构回旋管谐振腔并对其进行了理论分析和粒子模拟.研究结果表明,双共焦谐振腔中的高阶模式能够与高次电子回旋谐波发生稳定的相互作用,并且没有模式竞争现象,具备工作在太赫兹波段的潜力.相比普通共焦波导谐振腔,双共焦谐振腔能够增强准光回旋管的注波互作用强度,提高回旋管的输出功率和工作效率.此外,结果还表明双共焦波导中的电磁波模式是一种由两个独立的共焦波导模式叠加而成的混合模式.利用这种混合模式有望实现太赫兹回旋管的单注双频工作,为新型太赫兹辐射源的研究提供了新的途径. 相似文献
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K. D. Hong G. F. Brand P. W. Fekete T. Idehara 《International Journal of Infrared and Millimeter Waves》1992,13(2):215-227
The gyrotrons developed at the University of Sydney are tunable sources of millimetre and submillimetre radiation. The generation of submillimetre wavelengths requires operation at the second harmonic of the electron cyclotron frequency, or higher. Our latest gyrotron, GYROTRON IVA, has successfully achieved second harmonic operation and obtained frequencies up to 590 GHz (=0.51 mm). The experimental results and conditions for second harmonic operation will be presented. The design of a new gyrotron, GYROTRON V, which is especially optimised for the second harmonic, will also be included. 相似文献
16.
This paper describes a new second harmonic gyrotron cavity based on the concept of an internal Bragg-type grating which favors operation at the second harmonic of the electron cyclotron frequency rather than operation at the electron cyclotron frequency itself. 相似文献
17.
Hornstein MK Bajaj VS Griffin RG Temkin RJ 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2006,34(3):524-533
We report the regulated continuous-wave (CW) operation of a second harmonic gyrotron oscillator at output power levels of over 8 W (12.4 kV and 135 mA beam voltage and current) in the TE(0,6,1) mode near 460 GHz. The gyrotron also operates in the second harmonic TE(2,6,1) mode at 456 GHz and in the TE(2,3,1) fundamental mode at 233 GHz. CW operation was demonstrated for a one-hour period in the TE(0,6,1) mode with better than 1% power stability, where the power was regulated using feedback control. Nonlinear simulations of the gyrotron operation agree with the experimentally measured output power and radio-frequency (RF) efficiency when cavity ohmic losses are included in the analysis. The output radiation pattern was measured using a pyroelectric camera and is highly Gaussian, with an ellipticity of 4%. The 460-GHz gyrotron will serve as a millimeter-wave source for sensitivity-enhanced nuclear magnetic resonance (dynamic nuclear polarization) experiments at a magnetic field of 16.4 T. 相似文献
18.
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
19.
定义了光子带隙谐振腔(photonic-band-gap cavity, PBGC)的等效半径,论证了使用该半径将PBGC等效为具有模式选择性的金属圆柱谐振腔的有效性,揭示了其在PBGC设计过程中的指导性作用.基于等效半径的运用,建立起光子带隙谐振腔回旋管振荡器(PBG回旋管)的自洽非线性理论,并对工作于TE32模的PBG回旋管作了理论分析和数值计算.目前的研究表明:高频电磁场沿角向呈行波或驻波的不同极化形式对PBG回旋管的注-波互作用过程具有较大的影响;较之电子回旋基波,该器件中二
关键词:
光子带隙谐振腔
等效半径
回旋管
自洽非线性理论 相似文献
20.
La Agusu T. Idehara O. Dumbrajs 《International Journal of Infrared and Millimeter Waves》2004,25(7):1023-1036
The TE6,11 mode has been selected as a candidate for the second harmonic operation of a terahertz gyrotron at 1007.68 GHz. The predicted efficiency is 8.6 percent for the output power 0.38 kW. Time-dependent, multi-mode calculations have been carried out to investigate stability of a single-mode operation at second harmonic. It has been found that with the beam current 0.111 A and the magnetic field 19.282 T the second harmonic operation in the TE6,11 mode is possible. 相似文献