To meet the need to transmit increasingly massive volumes of data, a more than 3 kW continuous wave (CW) Ka-band sheet beam traveling-wave tube (SB-TWT) is reported for the first time. Working under unsaturated drive, the maximum gain obtained is 29 dB with a sheet beam of 30.9 kV, 0.82 A, and the efficiency exceeds 24% with a single-stage collector depressed to −15 kV. The 1-dB bandwidth reaches 6 GHz from 26 GHz to 32 GHz and the bandwidth with output power greater than 2 kW can even reach 7GHz from 26 GHz to 33 GHz. The realization of 99.8% static transmission as well as over 97% actual CW transmission of sheet beam is verified successfully, which benefits from adopting periodic cusp magnet (PCM) focusing, and thereby total weight is less than 15 kg. The relevant experimental details are introduced in this letter.

Recent hot test details and inspiring results of the W-band lossy-dielectric-loaded gyrotron traveling-wave tube (gyro-TWT) developed at the University Electronic Science and Technology of China (UESTC) are reported in this letter. Measurement of the gyro-TWT had achieved a pulse output power over 100 kW with a broad bandwidth of 8.5 GHz (92.0~100.5 GHz). For the first time as we know, the W-band gyro-TWT can stably operate with a 10% duty cycle and the average output power is over 10.3 kW in the frequency range. Excellent stability, pure spectrum and mode patterns are all verified in the hot test experiment.

In this letter, a 20-kW-average-power Ka-band TE01 mode gyro-traveling wave tube (gyro-TWT) with a cut-off waveguide section is presented and verified by hot test experiment for the first time. To improve the average output power, the new type gyro-TWT adds a cut-off waveguide in high frequency beam-wave interaction circuits. The large signal nonlinear theory calculations and particle in cell (PIC) simulations show that the new type gyro-TWT has broadband and high-power output performances. The hot test experiment shows that the measured maximum average power is 20.3 kW at 34 GHz, corresponding to a saturated peak power of 169.2 kW, a saturated gain of 52 dB, an efficiency of ~26.9%, and 3 dB bandwidth of 3.2 GHz.

Gyrotron traveling-wave tubes (gyro-TWTs) have been proved to be an attractive power source in many applications such as high-resolution radars, high-power communication systems, and electronic warfare systems. The main output indexes such as peak and average output power, interaction efficiency, and bandwidth are important for these devices. In addition, a great deal of reliability requirements such as nonstop stable operating time, operation lifetime, and environmental adaptability should be met. In this paper, detailed developing processes of gyro-TWTs in high average power operations are presented, including theoretical analyses, multiphysics simulations of key components, fabrication, and construction of the automatic hot test platform. Finally, the measured results of a Ka-band gyro-TWT for industrial applications are presented. The amplifier exhibits an excellent performance of 100-h nonstop stable operation, a 1-dB fraction bandwidth of 8%, an efficiency of more than 20%, and a peak power and an average power of more 150 and 10 kW, respectively.

A periodic dielectric meta-surface output window was cold and hot tested to extend the operating bandwidth and suppress the parasitic oscillations for a W-band wideband TE ₀₁ mode gyrotron traveling wave tube (gyro-TWT) in this letter. The fabricated beryllium oxide meta-surface dielectric window demonstrates a relative bandwidth of 37.84% with the reflection below −20 dB in the range of 75–110 GHz. The influences of engineering factors and machining errors on the performance are investigated and analyzed. Thermal analysis shows the average power handling capability of the window is over 33 kW within a wide frequency range. Hot test results demonstrate that the meta-surface window is excellent for oscillation suppression and the power handling capability is predicted larger than 20 kW.

Overall design and cold test of a G-band gyrotron traveling-wave tube (gyro-TWT) amplifier are presented. This gyro-TWT aims at achieving a goal of 10-kW pulse output power in the range of 210–220 GHz. It is operated in a circular TE ₀₁ mode at the fundamental cyclotron harmonics, which is driven by a 50-kV, 3-A gyrating electron beam. Low velocity spread diode-type magnetron injection gun (MIG), multichannel TE ₀₁ mode input coupler, broadband metasurface output window, and lossy material loaded beam–wave interaction circuit are simulated and partially measured. Particle-in-cell (PIC) simulation shows that the designed gyro-TWT can achieve a saturated output power over 10 kW in the range of 210–228 GHz with a beam velocity spread of 2.29%.