OUTGASSING OF A THIN WALL VACUUM INSULATING PANEL

A dewar flask of unusual shape using a thin wall flat metal panel is d escribed. Long operating time (similar to 10 years) sets strict requir ements for tightness and outgassing rate; the latter should be below 1 0(-15) mbar I s(-1) cm(-2). This is even lower than values met with UH V chambers, where hydrogen outgassing is the most serious problem. The aim of the work was to find a correlation of bake-out procedure and r esulting room temperature outgassing rate. Experimental procedures and results of gas pressure rise measurements with spinning rotor gauge ( SRG) on test samples are given. From the first 2000 h, extremely low o utgassing rate of q(out) similar to 10(-17) mbar l/(s. cm(2)), was fou nd. The results are compared to the reported data for stainless steel chambers of different wall thickness using the dimensionless Fourier n umber scale. (C) 1998 Elsevier Science Ltd. All rights reserved.