The 3.7 GHz high power klystrons TH2103A are widely used in the lower hybrid current drive system for the tokamak experiment. In order to avoid the tetrode and simplify the power supply system, the cathode modulation for high power TH2103A klystron is experimentally studied. Both the independent Anode Power-Supply (APS) and a Passive Potential Divider (PPD) configuration are investigated. The beam current goes to zero in 10 ms in the APS mode directly. As a result, a stable beam current is achieved in the PPD mode when the resistor from the anode to the ground is less than 30 k Ω, the cathode voltage is below − 45 kV and its rise-time is between 100 and 150 μs. The threshold of the resistor and the rise-time may be caused by the inductance of the wire-wound resistors. Although the anode current exceeds 10 mA when the cathode voltage rises and falls, 5 years operation validates the safety of the klystron. A practical and simple method is developed to operate the anode modulation klystron by cathode modulation on HL-2A, without using a dedicated tetrode.

中文翻译：

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HL-2A托卡马克TH2103A速调管阴极调制实验研究

3.7GHz大功率速调管TH2103A广泛用于托卡马克实验的低混合电流驱动系统。为了避免四极管和简化电源系统，对大功率TH2103A速调管的阴极调制进行了实验研究。研究了独立阳极电源 (APS) 和无源分压器 (PPD) 配置。在 APS 模式下，束流在 10 ms 内直接变为零。因此，当从阳极到地的电阻小于 30 k Ω，阴极电压低于 − 45 kV 并且其上升时间在 100 到 150 μs 之间时，在 PPD 模式下可以获得稳定的束流。电阻的阈值和上升时间可能是由绕线电阻的电感引起的。虽然阴极电压升降时阳极电流超过10 mA，但5年的运行验证了速调管的安全性。开发了一种实用且简单的方法，通过在 HL-2A 上进行阴极调制来操作阳极调制速调管，而无需使用专用四极管。