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The results of stabilization of both output power and frequency by double PID feedback control of the acceleration and anode voltage in the 460 GHz Gyrotron FU CW GVI (“Gyrotron FU CW GO-1” as an official name in Osaka University) are presented. The experiment based on the cyclotron frequency modulation by modulation of acceleration voltage of beam electrons and on pitch factor modulation by modulation...
We present results of theoretical study of influence of the electron velocity spread and the radial width on the efficiency and mode competition in a 300-GHz gyrotron operating in the TE22,2,1 mode, with which 300-kW level high power single mode oscillation has been demonstrated. Effects of a finite voltage rise time corresponding to the real power supply of this gyrotron is also considered. Simulations...
The results of both gyrotron output power and frequency stabilization by double PID feedback control of acceleration voltage and anode voltage have been presented. The second harmonic 460 GHz Gyrotron with isolated collector has been used in the stabilization experiment. In the long term experiment, the frequency stabilization was better than 10−6 and the power stabilization was better than ±1%.
Sub-THz gyrotrons with the functions of frequency control are useful for application to high power sub-THz spectroscopy including a DNP enhanced high-sensitive NMR spectroscopy. Continuous frequency tunability, frequency modulation and frequency step-changing will be achieved for our Gyrotron FU CW Series and such special functions of frequency control are applied for additional enhancement of NMR...
A Broadband frequency tunable gyrotron operating at fundamental resonance for 600 MHz DNP-NMR has been developed. A cavity resonator and a magnetron injection gun are newly designed. In the preliminary experiments, the continuously frequency tuning bandwidth was 1.3 GHz and the output power was increased up to 100 W.
A method is described to form a laminar electron beam for a high power gyrotron. An optimum potential profile is investigated to adjust each electron trajectory in between cathode and 1st anode. A high quality laminar beam is realized with a wide operation window.
Development of two 460 GHz second harmonic gyrotrons for 700 MHz DNP-NMR spectroscopy is presented. One gyrotron is frequency-fixed and the other is frequency tunable in the bandwidth of 1.5 GHz. In addition, the former has a function of frequency modulation.
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