Installation, preoperational testing and initial operation of the TFTR neutral beam deuterium-tritium gas delivery system

The Gas Delivery System for the TFTR Neutral Beam (NB) Heating System has been replaced with a new system which permits injection of either hydrogen/deuterium or tritium into each of the twelve Long Pulse Ion Sources (LPIS). The new gas delivery system will provide throughputs up to 100 torr-l/s of deuterium or 50 torr-l/s of tritium to each of the LPISs. The desired gas can be selected and the throughput adjusted between pulses on an individual source basis. The throughput is maintained uniform to ±1% throughout the injection pulse by utilizing a closed loop controller which varies the voltage applied to a piezoceramic element within piezoelectric valve as a function of the measured pressure within individual local storage plenums. The capability to “condition” the LPISs with deuterium between tritium injection pulses and maximum operational flexibility is provided by installing independent deuterium and tritium subsystems on each LPIS, A programmable logic controller provides central control, interlocks and permissives for all twelve LPISs. This paper presents the final installation and the results from preoperational testing and initial operation of the Neutral Beam Deuterium-Tritium Gas Delivery System (NB D-T GDS)