Engineers from F4E, ITER Japan, Consorzio RFX, ITER Japan, ITER Organization, and the companies involved in the fabrication of the power supplies of MITICA – an experiment testing a Neutral Beam Injector (NBI) prototype similar to that of ITER – met in Padua to put their pieces of equipment to a series of tests. Years of work had gone into the production of the High Voltage Deck (HVD) and High Voltage Bushing Assembly (HVBA), procured by F4E, manufactured by Siemens and its subcontractors Andreas Karl, and HSP. ITER Japan has been responsible for the procurement of the other equipment: a 1 MV Insulating Transformer manufactured by Hitachi, in addition to a long 1MV transmission line already tested.
The members of the various teams crossed Europe and Asia to meet under the same roof in the control room of the experiment. Others joined remotely to offer expertise as they all were getting ready for the moment of truth. When MITICA is operational, negative ions will be accelerated at 1MV – a speed and energy level that no other neutral beam system has achieved before. Would the HVD and HVBA reach the voltage level of 1.2 MV for at least one hour without any discharge and breakdowns? Would the European and Japanese pieces of equipment work jointly in a flawless manner? The results of the factory acceptance tests, carried out two years ago were positive. This time, however, the setup was different. The equipment was inside MITICA’s High Voltage Hall (HVH), next to other components, and the joint operation of the European and Japanese sub-systems raised the levels of complexity. On top of that, the team of engineers had to make a series of technical adjustments in order to improve the performance of the equipment operating with High Voltage. And here is another detail making the whole operation even more challenging: due to the stress that the equipment would be subjected to, it was decided to perform the more demanding tests once. It’s what you call a make-or-break-situation.
A line up of three types of tests was scheduled early in morning lasting in total seven hours: i) an hour at 1.2 MV ii) five hours at 1 MV and iii) five impulse tests at between 1 and 1.2 MV involving the components of Europe and Japan. All eyes were glued on the monitor of the MITICA control room, given the fact that the engineers were not allowed to access the hall for safety reasons. A special camera was monitoring in real time the effects of high voltage on the equipment. Each test had its own technical challenges and they were all tackled successfully. The completion of the final one triggered off a loud round of applause. They made it! The teams had managed several things in one go: to verify the suitability of the equipment; to operate and to test jointly the different components, and last but not least, they managed to meet the demanding objectives of the High Voltage (HV) acceptance tests. The next HV integrated test is planned for this autumn when the sub-systems will be officially handed over to ITER Organization.
“The system and its operation at 1 MV are unprecedented,” says Tullio Bonicelli, F4E Programme Manager for Neutral Beam, Electron Cyclotron and Power Supplies Systems. “It is an outstanding achievement resulting from the efforts and collaboration of many teams involved: F4E, ITER Japan, ITER Organization and Consorzio RFX, relying on the excellent contributions of the companies involved such as Siemens and Hitachi. Reaching this milestone has not been easy because we had to overcome several technical difficulties. The successful completion of these tests shows that even the most demanding requirements set by ITER, going beyond the state-of-the-art, can be successfully met.”