The fast pressure monitoring system on JT-60

Abstract

Fast pressure gauges have been installed in JT-60 to monitor the pressure near a plasma. They are Penning configuration gauges. A Penning discharge in the cell is sustained by the magnetic field which confines the plasma. The gauges are controlled by a personal computer. The main features of the system are as follows: a) the response time is fast (210 ms), and b) the structure is so simple that the gauges are reliable for use in severe conditions in JT-60. The system is successfully used over a year without maintenance. In this paper, the details of this fast pressure monitoring system are described.