The wall conditioning techniques in RFX

The vacuum vessel of RFX has a total volume of 10 m(3) and a surface exposed to the vacuum of 40 m(2). It is completely covered with 2016 graphite tiles. The following wall conditioning techniques are applied: baking up to 350 degrees C, GDC and PDC in H-2 and He. Moreover, in order to reduce Z(eff) in the plasma discharge, a GDC assisted deposition of a film containing boron has been carried out The effectiveness is assessed by means of mass spectrometers and by silicon samples exposed to the processes. In this paper, after a brief description of the wail conditioning techniques, the main results are reported and compared. Copyright (C) 1996 Published by Elsevier Science Ltd.