The JET neutral beam test bed facility and first results

The JET Neutral Beam Test Bed is installed in the Hot Cell next to the JET Torus Hall, where sufficient shielding is provided for operation with Deuterium Beams at 160 kV. The Test Bed is designed for simultaneous operation of two ion beams of 4.8 MW each with a pulse length of up to 30 s. Operation started at the end of 1983 and was initially limited by the commissioning of the power supplies complete in parallel, into resistive loads. So far the main achievements are; Running up the system to full performance of 80 kV, 17 s, 63 A with one beam source, where beam operation has revealed several weak points of the power supplies which could not be detected during the resistive load tests, Commissioning and improvements of the control and data acquisition system. In particular the turnaround time is still a problem and needs further improvement, and, Testing of the high heat transfer components used for scrapers and Ion Dump of which these components proved to be fully adequate showing no sign of excessive loading