共查询到20条相似文献,搜索用时 15 毫秒
1.
T. Idehara S. Mitsudo M. Pereyaslavets Y. Shimizu I. Ogawa 《International Journal of Infrared and Millimeter Waves》1999,20(7):1249-1270
At certain gyrotron operating conditions, mode cooperation instead of mode competition takes place between a fundamental and a second harmonic mode. This means the phase bunching of a gyrating electron beam under the second harmonic operation reduces the starting current for the fundamental operation and increases total output power as well as beam efficiency. Such mode cooperation is observed in experiments and confirmed by computer simulations for submillimeter wave Gyrotron FU II. 相似文献
2.
T. Idehara K. Ichikawa I. Ogawa T. Tatsukawa G. F. Brand 《International Journal of Infrared and Millimeter Waves》1998,19(12):1607-1625
Amplitude modulation in submillimeter wave gyrotrons resulting from the modulation of the anode voltage of electron gun is studied in detail. Computer simulations for the nonlinear regime, where the modulation rate of the anode voltage is not proportional to the amplitude modulation, model the experimental results quite accurately. 相似文献
3.
T. Idehara I. Ogawa K. Kawahata H. Iguchi K. Matsuoka 《International Journal of Infrared and Millimeter Waves》2004,25(11):1567-1579
Gyrotron FU II has been successfully applied as a submillimeter wave radiation source to plasma scattering measurements on the Compact Helical System (CHS) in National Institute for Fusion Science (NIFS) in Japan. The gyrotron operates in a long pulse mode (the pulse width is about 600 ms) at a frequency of about 350 GHz (the corresponding wavelength is 0.85 mm). The output power is about 110 W. The output power is transmitted along a circular waveguide system and converted to a Gaussian-like beam by a quasi-optical antenna. After that, the beam is directed onto the CHS plasma and the scattered signal is detected by a homodyne detection system. The frequency and the wave number of the scattered signal are analyzed. The results suggest that a broad band low frequency (several tens to several hundreds kHz) density fluctuation is excited in the CHS plasma only during neutral beam injection (NBI) or ion cyclotron resonance (ICR) heating. 相似文献
4.
T. Idehara N. Nishida K. Yoshida I. Ogawa T. Tatsukawa D. Wagner G. Gantenbein W. Kasparek M. Thumm 《International Journal of Infrared and Millimeter Waves》1998,19(7):919-930
The cavity of the newest gyrotron, Gyrotron FU IVA in the high frequency series of Fukui University gyrotrons (the Gyrotron FU series) is designed to minimize the mode conversion from the main cavity mode to the higher modes. In this paper, the experimental results are compared with simulations for the complete gyrotron oscillator. The gyrotron has an additional advantage to cover the wide frequency range in submillimeter wave region. 相似文献
5.
T. Idehara K. Yoshida N. Nishida I. Ogawa M. L. Pereyaslavets T. Tatsukawa 《International Journal of Infrared and Millimeter Waves》1998,19(6):793-801
The first cw operation of our submillimeter wave gyrotron (Gyrotron FU IV) using a 12 T superconducting magnet has been successfully carried out. Output power is more than 20 W at a frequency of 301 GHz in the TE031 resonant cavity mode. Time-resolved frequency measurement s shows that the frequency fluctuation of the gyrotron output is smaller than 2 MHz. This frequency fluctuation is mainly due to the fluctuation in the output voltage of the power supply. 相似文献
6.
T. Idehara K. Shibutani H. Nojima M. Pereyaslavets K. Yoshida I. Ogawa T. Tatsukawa 《International Journal of Infrared and Millimeter Waves》1998,19(10):1303-1316
Electron beam misalignment in a submillimeter-wave gyrotron strongly affects its total efficiency as well as excitation of rotating and counterrotating modes. Some of misalignment phenomena were studied theoretically and experimentally. 相似文献
7.
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
8.
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
9.
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
10.
S. P. Sabchevski G. M. Mladenov T. Idehara 《International Journal of Infrared and Millimeter Waves》1999,20(6):1019-1035
The software package GUN-MIG has been developed for computer simulation of beam formation in magnetron injection guns (MIG). It is based on a fully relativistic self-consistent physical model which takes into account the specific problems and requirements that are being encountered in the analysis and design of MIG for gyrotrons. Besides providing a general outline of the physical models and the program implementation of the code, several illustrative examples of the numerical experiments with real MIG for submillimeter wave gyrotrons are presented and discussed. 相似文献
11.
M. Pereyaslavets I. Ogawa T. Idehara S. Mitsudo 《International Journal of Infrared and Millimeter Waves》1999,20(8):1453-1468
The excitation and transmission losses of a dielectric-lined waveguide have been calculated with real, experimentally measured output beams of a submillimeter wave gyrotron. It is shown that for not-so-long transmission lines the coupling losses far exceed the transmission losses in the waveguide. 相似文献
12.
Observation of Mode Patterns for High Purity Mode Operation in the Submillimeter Wave Gyrotron FU VA
T. Idehara I. Ogawa S. Maeda R. Pavlichenko S. Mitsudo D. Wagner M. Thumm 《International Journal of Infrared and Millimeter Waves》2002,23(9):1287-1295
Operation tests of a cavity designed for high purity mode operation of the submillimeter wave gyrotron FU VA has been carried out successfully. The observed emission patterns of several cavity modes appear very pure and are compared with calculated results. High purity mode operation has the advantage of making the conversion to Gaussian-like beams more efficient. 相似文献
13.
Observation of Mode Patterns for High Purity Mode Operation in the Submillimeter Wave Gyrotron FU VA
T. Idehara I. Ogawa S. Maeda R. Pavlichendko S. Mitsudo D. Wagner M. Thumm 《International Journal of Infrared and Millimeter Waves》2002,23(7):973-980
Operation tests of a cavity designed for high purity mode operation of the submillimeter wave gyrotron FU VA has been carried out successfully. The observed emission patterns of several cavity modes appear very pure and are compared with calculated results. High purity mode operation has the advantage of making the conversion to Gaussian-like beams more efficient. 相似文献
14.
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
15.
Zhang Xun Zhang Ping Chen Weibin Xiao Dongmei Luo Xizhang 《International Journal of Infrared and Millimeter Waves》2003,24(7):1101-1111
Based on the theory of molecular vibration relaxation, the model of buffer gas effect was built up. By theoretically deducing the vibrational lower-level deactivation rate of operating gas molecule with quantum mechanics, the selection rules of high-efficient buffer gas under different working conditions were educed and tested by experiments. The results could be helpful to the study of large-power wide-range efficient tunable miniature pulsed optically pumped submillimeter wave laser and its application. 相似文献
16.
T. Idehara T. Saito H. Mori H. Tsuchiya La Agusu S. Mitsudo 《International Journal of Infrared and Millimeter Waves》2008,29(2):131-141
Long pulse operation up to 1 msec of a high frequency gyrotron with a pulse magnet has been successfully carried out in a
frequency range including 1 THz. In the experiments, the timing of an electron beam pulse injection is adjusted at the top
of the magnetic field pulse, where the variation of field intensity is negligible. The operation cavity modes seem to be TE1, 12 and TE4,12 at the second harmonics. The corresponding frequencies are 903 GHz and 1,013 GHz, respectively. Additionally several features
of radiation measurement results of the gyrotron are described and brief considerations are presented. 相似文献
17.
Zhang Xun Zhang Hongjie Zhang Ping Chen Weibin Luo Xizhang 《International Journal of Infrared and Millimeter Waves》2003,24(11):1967-1976
Based on the basic theory of molecular vibration relaxation and semi-classical density matrix theory, operating parameters optimization of buffer gas in the process of miniature pulsed optically pumped submillimeter wave laser was systemically studied and the theoretical calculated result was tested by experiments. The result would do favor to develop and study high-power and wide-range tunable miniature and high-efficient pulsed optically pumped submillimeter wave laser and also had some instruction to its application. 相似文献
18.
S. Sabchevski T. Saito T. Idehara T. Nakano Y. Tatematsu 《International Journal of Infrared and Millimeter Waves》2007,28(12):1079-1093
A series of experiments carried out in order to study the operational performance and oscillation characteristics of a 300 GHz/3.5 kW
gyrotron FU CW I have demonstrated a complicated behaviour which is attributed to multimoding phenomena. In this paper we
present and discuss some initial results from computer simulation of mode interaction in this tube. They give a better insight
in the underlying processes, possible excitation conditions of various competing modes and suggest some directions for continuation
of this investigation. 相似文献
19.
Xun Zhang Dongmei Xiao Xizhang Luo Huanhui Liang Ping Zhang 《International Journal of Infrared and Millimeter Waves》2002,23(7):1047-1056
Based on semi-classical density matrix theory, multi-Raman interaction in multi-longitudinal-mode CO2-9R (30) optically pumped NH3 molecules laser was studied theoretically. With different parameters such as pumping power and operating gas pressure, the effect of multi-Raman interaction and the longitudinal-mode structure of submillimeter wave laser were also discussed. 相似文献
20.
Luo Xizhang Zhang Xun Dong Hongyu 《International Journal of Infrared and Millimeter Waves》2002,23(1):21-32
Based on the semi-classical density matrix theory, multi-Raman processes in two-longitudinal-mode optically pumped cavity submillimeter wave laser were studied theoretically. And their effects on submillimeter wave laser spectral characteristics were discussed under different pump powers, operating pressures and laser tube lengths. 相似文献