Gas inlet control system for the stellarator TJ-II

This paper describes the Gas Inlet Control System for the TJ-II Stellarator, which is currently in operation in Madrid (Spain). This system is an essential control element of the TJ-II, which has been commissioned, designed, and built to provide the appropriate values of gas density during the whole evolution of the experimental pulses. The gas is puffed using a set of 8 piezoelectric valves, which is driven by a preprogrammed voltage signal. Mainly aperture time and the desired density inside the vacuum vessel define the signal profile. This density depends on a complex function of the voltage applied to the valve and the accumulated effect of consecutive inlets during a shot. An arbitrary waveform generator VME module generates the output signal In order to do all this in a friendly environment and with access from different hardware platforms, a graphical user interface has been developed using the JAVA programming language; so, all the parameters in the system can be fully configured using Internet applet viewers. This graphical application interfaces with the control software running on OS9 real time operating system. Specific socket and a web server are used on the VME crate side. Remote access to the system is allowed from computers in the TJ-II control Intranet.