Equivalent Model of Transient Gyrotron Cathode Response

TL;DR

This paper presents an equivalent circuit model of the gyrotron cathode to explain transient voltage and current phenomena observed during operation, aiding in the development of electron cyclotron heating systems.

Contribution

The paper introduces a novel equivalent circuit model of the gyrotron cathode that accurately explains transient behaviors observed in experiments.

Findings

The cathode voltage drops significantly during overcurrent conditions.

The equivalent circuit model matches experimental transient responses.

Analysis can improve gyrotron operation and system development.

Abstract

The gyrotron is the high power millimeter wave source in the electron cyclotron resonance heating system for the tokamak. The cathode power supply is one of the most important ancillary devices for gyrotron. Some interesting transient phenomena about the cathode voltage and the cathode current was found in the gyrotron operation in the electron cyclotron resonance heating system for the Experimental Advanced Superconducting Tokamak. The cathode voltage drops to about 10% of the original value by about 90 {\mu}s in the overcurrent case, which is much longer than the 25 {\mu}s in the normal case. In order to explain these phenomena, an equivalent circuit model of the magnetron injection gun was proposed. The equivalent circuit is composed of parallel resistors and capacitors, and it can explain the test results very well. Using the equivalent circuit model to analyze gyrotrons may become an effective means of developing and operating an electron cyclotron heating system.