Guangjiang Yuan

Operation of a Ka-band Harmonic-Multiplying Gyrotron Traveling-Wave Tube

Amplification studies of a Ka-band harmonic-multiplying gyrotron traveling-wave tube (gyro-TWT) are reported. A coupled cavity with inner- and outer-intersecting couplings and precise control of the focusing magnetic field are used to improve the coupling between the fundamental and the harmonic and to adapt the sensitivity of the effect of focusing magnetic field on the beam-wave interaction in the gyro-TWT to high-order mode operation. Experimental results show that 75 kW of peak output power with a bandwidth of 1.06% and a gain of more than 25 dB can be reached at a pulse voltage of 67.2 kV and a pulse current of 15.8 A.

Experimental Study of a Ku-Band Gyrotron Backward-Wave Oscillator With a Single Stage Depressed Collector

The experiment on a Ku-band gyrotron backward- wave oscillator (gyro-BWO) with a single depressed collector and linear polarization mode output has been performed successfully. Stable magnetic tuning bandwidth of 5% and maximum power of 48 kW under a 40-kV 11.5-A electron beam were achieved. The overall efficiency of the gyro-BWO with a single stage depressed collector has been enhanced from 10.5% to 21%. The measured performance has demonstrated a strong potential of the gyro-BWO for new application requiring high-power tunable wave source.

First Experiment and Design of a Harmonic Multiplying Gyrotron Traveling Wave Amplifier with the TE02 Mode Output

A harmonic multiplying gyrotron traveling wave amplifier with the TE02 mode output has been designed in Institute of Electronics, Chinese Academy of Science (ECAS). First experimental results showed that the tube could stably amplify input signal, the output frequency bandwidth of more 500 MHz (33.02-33.524 GHz) had been reached at output pulse power of 10.07~12.88 kW, beam voltage of 60 kV, beam current of 11 A.

A Harmonic Multiplying Gyrotron Traveling Wave Amplifier with the TE02 Mode Output

For a gyro-amplifier, harmonic multiplying can lower the applied magnet field and more easily get RF driver. Theoretical studies and numerical simulation had been made in the references (G.S. Nusinovich et al., 2001), (K.R. Chu et al., 1997), (A.T. Lin et al., 2002) for the amplifier. Experimental results ever reported for a third-harmonic multiplying gyrotron travel wave amplifier (Chan-Wook Baik et al., 2005). In this paper, the simulations, designs and experimental results of a second-harmonic multiplying gyrotron traveling wave amplifier with the TE02 mode output was discussed.

Research progress of the harmonic multiplying gyrotron traveling wave amplifier at Ka band in IECAS

In this article, a new method is utilized for enhacing output power and improving bandwidth. The works related to harmonic multiplying gyrotron traveling wave amplifier were ever reported by us in IRMMW2006 and IVEC2007, which showed that there were some contradictions between output power and band-width. The output frequency bandwidth of more 500 MHz can be reached at output pulse power of only 10.07~12.88kW. Output pulse power can be increased to 25 kW with very narrow bandwidth. Because of using harmonic multiplying, the resonant circuit is usually used to increase the coupling between fundamental and harmonic. However, it will decrease operating bandwidth.

Operation of a Ka-band harmonic multiplying gyrotron traveling wave tube

Amplification studies of a Ka-band harmonic multiplying gyrotron traveling wave tube are reported. Coupled cavity and the precise control of focusing magnet field were used to improve the coupling between the fundamental and the harmonic and to adapt the sensitivity of the effect of focusing magnet field on the beam-wave interaction in the tube with a high order mode operation. Some experimental phenomena were also discussed.

A New Type of Coupled Cavity Interaction Circuit for Gyrotron Traveling Wave Amplifier Applications

This paper proposes a new type of coupled-cavity interaction circuit for gyrotron traveling-wave amplifier applications with inner- and outer-intersecting coupling. For analysis, we use the equivalent-circuit method, as well as the Ansoft High Frequency Structure Simulator (HFSS) code. Calculated results for the frequency characteristics of the interaction circuit show that at the center frequency of 17.2 GHz a 3-dB bandwidth of more than 533 MHz (3.5% relative bandwidth) may be reached with the TE10 \square rectangular guide mode as input and the TE01 \bigcirc cylindrical guide mode as output.

A harmonic multiplying gyrotron traveling wave amplifier at Ka band developed in IECAS

The works related to harmonic multiplying gyrotron traveling wave amplifier were ever reported by us in IRMMW2006 and IVEC2007, which showed that there were some contradictions between output power and band-width.[1, 2] In [1], the output frequency bandwidth of more 500 MHz can be reached at output pulse power of only 10.07~12.88kW. In [2], output pulse power can be increased to 25kW with very narrow bandwidth. Because of using harmonic multiplying, the resonant circuit is usually used to increase the coupling between fundamental and harmonic. However, it will decrease operating bandwidth. In this article, a new method is utilized for enhacing output power and improving bandwidth.

Influence of interface status on heat dissipation capability of collector for travelling wave tube

In the paper, Influence of interface status (ratio of brazing area and fit clearance) of brazed collector parts on contact heat resistance was theoretically analysised. And by ANSYS simulation, influence of ratio of brazing area and fit clearance on heat dissipation capability of collector for travelling wave tube was studied.

P3-11: Some phenomena in the experimental process of a harmonic multiplying gyrotron traveling tube

Some experimental phenomena of a harmonic multiplying gyrotron traveling wave tube operating in 8mm band has been discussed in this extended abstract, it has been found that the output power of the tube decreased with the increase of the filament power and its bandwidth increased with the decrease of the output power for the same beam current.