Design and Development of DC Power Supply System for 1.5MW, 40MHz, RF Amplifier

Abstract

A 1.5 MW RF (ap40 MHz) amplifier using Eima tetrode 4CM2500KG is in the testing phase, here at Institute for Plasma Research (IPR). This amplifier is being developed for the ion cyclotron resonance heating (ICRH) system of Super Conducting Steady State Tokamak, SST1. This RF amplifier amplifies an input power of 200 kW to about 1.5 MW. Few DC power supplies are needed for the operation of this amplifier such as plate supply, screen supply, filament supply, and grid supply. We have a conventional HVDC power supply rated for 60 Kv@10 A for the preliminary testing of this RF amplifier. The required RHVPS (25 Kv@120 A) for this amplifier is under development, hence it is beyond the scope of this paper. This amplifier needs about 10 kW (15 V@650 A) of DC power for heating its filament. We have developed a DC power supply of 12kW (15 V@800 A) to feed the heater. Also, the amplifier needs about 4 kW (500 V@8 ADC) and 6 kW (1500 V@4 A) of DC power to feed its control grid and the screen grid, respectively. So, we have developed another two DC power supplies capable of delivering 6 kW (600 V@10 A) and 7.5 kW (1500 V@5 A) to bias the control grid and screen grid of this amplifier, respectively. These power supplies are to be remotely operated from a PC located at a distance of about 20 to 50 meters. Also, there are some interlocks needed among these power supplies and with the plate HVDC power supply, for the stable and safe operation of the amplifier. In this paper, the test results of all these power supplies on a dummy load will be presented