GRAPHITE DUMPS FOR NON NEUTRALIZED IONS IN TFR NEUTRAL INJECTORS
Graphite has been chosen because of low Z and good thermal behaviour. Design parameters are: a set of 8 x 8 cm**2, 1 cm thick graphite tiles mechanically assembled on a water cooled copper and stainless steel structure to form 80 x 32 x 2.5 cm**3 shields. At a maximum power density of 2-4 kW/cm**2 the surface temperature rise is around 450-900 degrees C after 0.1 s. With a repetition rate of 2-4 minutes, the average power is less than 150 W per tile. A simple plane contact, with screws exerting a force of 100-200 kg on 2 cm**2, gives a thermal conductance of about 2 W/degrees C per tile, which implies a cool down time constant of about 5 minutes. Radiation losses are still low enough for calorimetric energy measurements. These figures were obtained by testing a 4-tile prototype under real beam conditions. Moreover, impurity yield and outgassing have also been investigated under real power density and geometry conditions, by intercepting with a movable graphite plate half of a neutral beam and looking for losses on the other half. Attenuation of the latter was less than 2%. With regard to the demands of future systems, the high power densities of this design cannot be extrapolated to long pulse operation. The surface temperature rise is the limiting factor.
Bibliographic Reference: 4TH INTERNATIONAL SYMPOSIUM ON HEATING IN TOROIDAL PLASMAS, ROMA (ITALY), MARCH 21-28, 1984 VOL. II, PP. 1378-1381 1478 P., VOL. I AND VOL. II, 1984 WRITE TO MONOTYPIA FRANCHI, ST. LUCIA - VIALE UMBRIA NO. 28, 06012 CITTA DI CASTELLO, PERUGIA (ITALY), PRI
Record Number: 1989124042800 / Last updated on: 1987-01-01
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