Stabilization and modulation of the output power of submillimeter wave gyrotron

Abstract

High frequency, medium power gyrotrons (Gyrotron FU series) have been developed at the Fukui University as radiation sources convering a broad frequency band from millimeter to submillimeter wave region. We have performed cw operation of the Gyrotron FU IV. However, the output power was not stable (approximately several tens %) due to the fluctuation of the cathode potential (40 V). The output power was stabilized within several percent by controlling the anode potential. Such a technique was also used for amplitude modulation of the gyrotron output. Improved stabilization of output power and effective modulation will be achieved by stabilizing the cathode potential

Gyrotron FU CW VII for 300 MHz and 600 MHz DNP-NMR Spectroscopy

“…Radiation peaks coming from the designed cavity modes TE 13 and TE 42 are observed only in Fig. 3 at the field intensities of 6.83 T and 7.42 T. While, the radiation peak from the cavity mode TE 16 appears in both figures at the field intensity of 7.22 T.…”

“…The diameter of the room temperature bore is 88 mm and the uniformity of the field distribution at the center of the magnet is better than 0.1 percent within 86.4 mm in axial direction. The designed cavity modes are TE 13 and TE 42 modes for the fundamental operation modes and TE 16 for the second harmonic mode.…”

“…Figure 2 shows the starting currents I st as a functions of magnetic field intensity B for many cavity modes operating at both the fundamental and the second harmonics. The designed cavity modes TE 42 , TE 13 and TE 16 can be excited when the beam current is…”

Long Pulse Operation of the THz Gyrotron with a Pulse Magnet

“…We are using a triode magnetron injection gun in order to control the beam parameters for modulation of amplitude and frequency [18,19]. The mirror ratio defined as B c /B g is varied from 84 to 127, where B c and B g are the magnetic field intensities at cavity region and gun region, respectively.…”

“…Among many radiation sources, the gyrotron is one of the most appropriate ones for such a objectives, because of high efficiency even in high frequency and high harmonics [4], stability of frequency and amplitude [18,19] and possibility of long pulse or CW operation in long time.…”