An upgrade of the RFX-mod experiment is in progress, involving a major change and reconfiguration of the inner components of the machine assembly. In particular, the present vacuum vessel will be replaced by the external stainless steel toroidal support structure, which will be significantly modified with the integration of approximately 150 vacuum-sealed ports, interfaced with existing machine sub-systems (diagnostics, pumping and fuelling), and the implementation of 2 vertical and 2 horizontal vacuum-tight electrically-insulated crossed joints, necessary to allow suitable penetration of electromagnetic fields within the plasma chamber. The design of such peculiar joints of the vessel required the development of several mock-ups in which different solutions and arrangement of materials have been tested. The final solution implies the use of high-performance polymers combined with acrylic based syntactic foam materials, which provide proper vacuum tightness (required leak rates < 1E-9 mbar·l/s) and electrical insulation (required dielectric strength > 1 kV/mm), with suitable viscoelastic characteristic that guarantees the compensation of thermal deformations expected during operation. The paper will describe the numerical FEM analyses performed to verify thethermo-mechanical design of the system at the operating conditions and the experimental tests, in particular leak tests and outgassing tests, carried out on mock-ups to assess the reliability of the design solution.
Design and Test of the Vacuum-tight Electrically-Insulated Crossed Joints of the New Vacuum Vessel for the RFX-mod2 Experiment
Dalla Palma M;Rossetto F;
2019
Abstract
An upgrade of the RFX-mod experiment is in progress, involving a major change and reconfiguration of the inner components of the machine assembly. In particular, the present vacuum vessel will be replaced by the external stainless steel toroidal support structure, which will be significantly modified with the integration of approximately 150 vacuum-sealed ports, interfaced with existing machine sub-systems (diagnostics, pumping and fuelling), and the implementation of 2 vertical and 2 horizontal vacuum-tight electrically-insulated crossed joints, necessary to allow suitable penetration of electromagnetic fields within the plasma chamber. The design of such peculiar joints of the vessel required the development of several mock-ups in which different solutions and arrangement of materials have been tested. The final solution implies the use of high-performance polymers combined with acrylic based syntactic foam materials, which provide proper vacuum tightness (required leak rates < 1E-9 mbar·l/s) and electrical insulation (required dielectric strength > 1 kV/mm), with suitable viscoelastic characteristic that guarantees the compensation of thermal deformations expected during operation. The paper will describe the numerical FEM analyses performed to verify thethermo-mechanical design of the system at the operating conditions and the experimental tests, in particular leak tests and outgassing tests, carried out on mock-ups to assess the reliability of the design solution.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
