A shiny metallic box measuring 4 x 4 x 4 metres, resting 6 metres above floor level on four large gas-insulated columns, located inside a futuristic-looking high-voltage laboratory makes for an impressive sight. Add the fact that this Faraday cage is subjected to voltages in excess of 1 MV (1 million volts, compared to 230V for a typical electrical domestic appliance) and it becomes even more remarkable. The box, a mock-up of the High Voltage Deck (HVD) for MITICA ; a test-bed currently being built at the Neutral Beam Test Facility (NBTF) in Padua, Italy, in order to test the Neutral Beam injectors that will heat the plasma in ITER; has been subjected to high-voltage testing in order to validate the design choices of the supplier SIEMENS AG. Withstanding such high voltages is extremely challenging and similar examples are very rare worldwide: checking of the test arrangements and meticulous adjustments are necessary before the actual tests can take place. Attended by staff from F4E and from Consorzio-RFX, the host of the Neutral Beam Test Facility, several electrical tests were carried out at the High-Voltage laboratory of Hochspannungsgeräte GmbH (HSP) in Troisdorf, Germany. These included one long-duration test (5 hours at 1.2 million volts DC) and several short-duration tests (impulses of 50 micro-seconds at 2.1 million volts) aiming to verify that the deck will sustain the different voltage levels which are expected during MITICA operation.
As HSP is a world-wide leader in producing high-voltage equipment, their testing facility is in high demand and therefore with limited availability. Both SIEMENS and HSP assembled the mock-up during the night preceding the tests In order to accommodate our stringent planning, says Muriel Simon, F4E’s Technical Officer in charge of the procurement of the high voltage deck for MITICA. “Thanks to their dedication and drive, all tests were concluded positively and on schedule, by the evening of the same day”, she enthuses.
The completion of these electrical tests constitute an important step towards the full manufacturing of the High Voltage Deck for MITICA, which will continue up to the end of the year. Its assembly at the NBTF site is scheduled to start in the spring of 2017.