NIFS-594

FULL TEXT (PDF, 479 KB)


Author(s):

Xiaodong Li

Title:

Analysis of Crowbar Action of High Voltage DC Power Supply in the LHD ICRF System

Date of publication:

Apr. 1999

Key words:

LHD, ICRF heating, Transmitter, DC power supply, Transformer

Abstract:

Ion Cyclotron Range of Frequency (ICRF) heating will be applied to the Large Helical Device (LHD) at the 2nd experimental campaign in 1998. The LHD ICRF systern is characterised by its high power (up to 12MW at final stage) and steady state operation for more than 30 minutes. One of the main R&D items was a high power and steady state transmitter. The RF transmitter system having a wide frequency range from 25 to 95 MHz was designed and fabricated. This report describes the analysis of the DC power supply that contains the crowbar circuit protecting the tetrode from the arcing inside the tube. The DC power supply of the transmitter is fed from the commercial AC electric line which also supply the power to the LHD helical and poloidal coil power supplies. The voltage drop of the commercial line when the ICRF crowbar action happened is the serious problem for all experimental system. This paper analyses the crowbar effect on the commercial line with and without leakage transformer between the step-up transformer of transmitter and the commercial line.

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