فعالیت های تحقیق و توسعه طراحی صفحه MITICA پلاسما درایور در فرایند تولید از طریق روش اتصال انفجارِی

The back plate of the MITICA plasma source, named Plasma Driver Plate (PDP), will be protected from the impact of the highly energetic back-streaming positive ions (BSI+), generated inside the accelerator, by a 1.0 mm thick molybdenum layer that will be joined by Explosion Bonding (EB) technique to the copper heat sink. This technology has been investigated and used for manufacturing prototypes, demonstrating very high strength of the obtained molybdenum–copper interface. The production of the shaped edge profile of the driver-hole, after the EB, is an open point. In order to demonstrate the possibility to produce the PDP by explosion bonding, the manufacturing of a full scale prototype of the area just around one of the PDP driver-holes was identified as the road to address most of the manufacturing issues. Elasto-plastic finite element analyses have been carried out to improve the hole rim geometry and the process parameters of all the manufacturing steps. A full scale prototype of the PDP driver-hole has been manufactured and tested. This contribution gives an overview of the R&D activities carried out to address the main open issues, to define the PDP component detailed geometry and its manufacturing processes, via EB technique.

Positive ions are expected to be produced by reactions between particles within the accelerator volume of the SPIDER and MITICA beam sources [1] and [2], and sent back towards the plasma source. Highly focused beamlets of H+/D+ and H2+/D2+, named Back Streaming positive Ions (BSI+), will hit the plasma source inner vertical rear plates, such as the Plasma Driver Plate (PDP) [3], causing physical sputtering on plasma facing material and additional heat load (with respect to the normal RF plasma–surface interactions). The very high particle energy and flux expected in MITICA impose the presence of a thick layer of Mo for withstanding the sputtering on the surface of the PDP. No consolidated industrial technologies are currently available for manufacturing coatings of molybdenum on copper with the required parameters (thickness of 1.0 mm, no porosity and strength of the interface) R&D activities have been carried out on this topic and the Explosion Bonding (EB) technology has been finally chosen for the manufacturing of the molybdenum armour layer of the MITICA plasma source. Prototypes produced by EB (1 mm Mo + 8 mm Cu) have successfully passed thermal and mechanical tests, demonstrating the good quality of the Mo–Cu interface. Delamination within the Mo thickness appeared instead at the driver-hole rim of the prototypes, after its warm forming, necessary for reaching the required shape of the PDP. Further activities were then identified in order to solve the open issues that still prevented from the possibility to manufacture the Plasma Driver Plate of MITICA by EB. Such activities and the obtained results are presented in this paper.