A gyrotron-traveling-wave tube amplifier experiment with a ceramic loaded interaction region

A Ka-band gyrotron traveling wave (gyro-TWT) amplifier with high power and wide bandwidth operated in the fundamental TE11 circular mode is presented in detail. The stability of the gyro-TWT amplifier using linear and nonlinear theory is analyzed. The distributed loss technique is employed in the interaction circuit which guarantees the amplifier zero-drive stability. The effects of the parameters such as input power, driver frequency, magnetic field on the performance of the gyro-TWT is discussed. The simulation results show that the gain and the bandwidth of the designed Ka-band gyro-TWT are about 60.0 dB and 1.4 GHz at constant drive with an axial velocity spread $v z =v z ¼ 5%. The peak output power and the corresponding electronic efficiency are about 111 kW and 26.4% respectively for a 70 kV, 6A electron beam at 35 GHz. In addition, the design of the input coupler, a triode-type magnetron injection gun (MIG) and a triple output window are given.

mentioning

confidence: 96%

Study of a Ka-Band TE11 Mode Gyrotron Traveling-Wave Amplifier

Liu

2010

“…In the United States, a TE 01 mode gyro-TWT has been developed at the Naval Research Laboratory (NRL), to provide the required loss for stable operation, the amplifier used a ceramic loaded interaction circuit. A saturated peak power of 137 kW was achieved at 34.1 GHz, a saturated gain of 47.0 dB, an efficiency of 17%, and a 3dB bandwidth of 1.11 GHz [7]. A mode-selective TE 11 mode gyro-TWT has demonstrated a measured peak output power of 78 kW, gain 60 dB, and a 3-dB bandwidth of 4.2 GHz [8].…”

mentioning

confidence: 97%

Design and Simulation of a Ka-Band TE11 Mode Gyro-Traveling-Wave Amplifier

Liu

Zhang

et al. 2009

The design of a Ka-band gyrotron traveling wave amplifier with high power and wide bandwidth is presented in detail. The amplifier operates in the TE11 circular mode at the fundamental cyclotron harmonic. The distributed loss technique is adopted in the interaction circuit which guarantees the amplifier zero-drive stability. The effects of the parameters such as input power, driver frequency and magnetic field on the performance of the gyro-TWT are discussed. The simulation results show that the gain and the 3dB bandwidth of the designed Ka-band gyro-TWT are about 56.0dB and 1.8 GHz ,respectively. The peak output power and the corresponding electronic efficiency are about 100 kW and 23.8% respectively with the voltage 70 kV and the current 6A at the velocity ratio 1.0.

“…But the gyro-TWT, which can potentially provide high power and broad bandwidth operation, is far less developed [1,5,6]. A gyro-TWT explores the convective instability of the ECM in a fast-wave traveling-wave circuit as its operating principle.…”

mentioning

confidence: 99%

“…But it suffers from severe challenges from the absolute instabilities [1]. A series of experimental and theoretical researches have revealed that introducing a certain kind of attenuation in the interaction circuit is a generally feasible way to stabilize these oscillations [1,[5][6][7]. The start-oscillation current is a preferable parameter to measure the stability of the system.…”

mentioning

confidence: 99%

Beam-Wave Coupling Strength Analysis in a Gyrotron Traveling-Wave Amplifier

Du¹,

Liu²

2010

Mode competition is an important aspect of the stability analysis of a gyrotron traveling-wave amplifier (gyro-TWT). The concept of the coupling impedance is developed in this paper to investigate the beam-wave coupling strength in the electron cyclotron maser (ECM) interaction system. The coupling impedance brings a global consideration to study competition between the absolute instability and the convective instability in the circuit. The research reveals that the coupling impedance is proportional to the phase velocity of the mode, which means the coupling impedance of a mode in the lower k z region is much stronger than the one in the higher k z region. Interesting discussions are also carried out at the end of the paper. The coupling impedance provides an additional dimension of measurement to understand the ECM interaction.