Lessons learned after three years of SPIDER operation and the first MITICA integrated tests
Introduction
The ITER Neutral Beam Test Facility (NBTF) is targeted at the development and testing up to nominal performances of the full-scale prototype of the ITER Heating Neutral Beam Injector (HNB) [1], [2], [3].
The NBTF is established in Padova (Fig. 1), integrated in an international framework of responsibility and collaboration among Consorzio RFX, ITER Organization (IO), Fusion for Energy and JADA/QST with the involvement of some European research institutes; it is strictly liaised with the Indian Test Facility (INTF) in charge of the ITER Diagnostic Neutral Beam (DNB) [4].
Two test beds are foreseen on NBTF site: SPIDER features the first prototype of ITER ion source, with strong similarities with DNB configuration, while MITICA is the 1:1 scale prototype of ITER HNB.
In 2021, after three years of operation, SPIDER entered a long shut down phase with the aim of solving issues arising and detected during the first operational phase. MITICA is in the final construction phase of the injector, with all the auxiliary systems installed and with the final integrated tests of the overall power supply underway.
Efforts are being paid in synergy with other experiments worldwide focusing on negative ion based neutral beams, in particular in Japan and India, in relation to their direct involvement in ITER and in the NBTF, and also in Europe, supported by EUROfusion, for the challenging RF source development.
Section snippets
SPIDER
SPIDER experiment (Fig. 2), the third leg in EUROfusion step ladder approach towards ITER source for NB injectors, together with BUG and ELISE at IPP-Garching [5], represents a novelty in the negative ion sources for many aspects related not only to the dimensions. Among the most impacting factors, it is necessary to highlight that, unlike any other existing NBIs, the entire beam source of SPIDER (and MITICA) lies inside the vacuum vessel, so that it is surrounded by the same background gas at
MITICA
MITICA, the one-to-one prototype for ITER HNB, is gradually approaching the start of operation.
Prior to that, three main areas of work are being dealt with in order to complete the whole experiment assembly, testing and commissioning:
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Last components/plants still under completion [43]
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Power supply integrated final tests and specific commissioning
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Preparation for a dedicated campaign of HV holding tests in vacuum
Conclusions
SPIDER is entering the first long shutdown after the first three years of experiments. Interesting results have been obtained at reduced performances, which have also identified necessary modifications, mainly focused on source upgrade, RF generators replacement and enhancement for the vacuum pumping system, in order to quest the target performances during the next operational phase.
MITICA is proceeding towards the end of preparatory activities prior to the start of the first experimental
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgment and disclaimer
This work has been carried out within the framework of the ITER-RFX Neutral Beam Testing Facility (NBTF) Agreement and has received funding from the ITER Organization.
This work has also been carried out within the framework of the EUROfusion Consortium, it has been funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 — EUROfusion).
Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the
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