The choice of dielectric material for the (double) dielectric window of the ITER ICRF Transmission Line is optimized with respect to nuclear, mechanical, and thermal properties. Neutron fluence at the window placed in the vacuum vessel feedthrough is obtained with MCNP-4 to be sufficiently small for allowing beryllia, but not alumina without additional neutron shielding, to be used as dielectrics. For beryllia (10−3 dpa) or for unirradiated alumina, the temperature is found to stay between the cooling temperature and 200°C with maximum hoop stress less than 100 MPa, provided titanium, niobium or materials with similar thermal expansion coefficients are used as support. Based on experimental vacuum tightness and shear strength tests for alumina-titanium joints, three potential brazing filler metals have been identified for bonding.
|Fusion Technology 1996
|16/09/96 → 20/09/96