3.1.2. Comparison before and after bake-out
Fig. 5 shows the sample no. 5, which was cleaned with the pro-
cedure B (cp. 2.4). The mass spectra before and after a bake-out
sequence (3.5 h at 150 ◦C) are shown. Clearly the improved residual
spectrum and cleaning effect is visible.
3.1.3. Comparison of different cleaning procedures
A comparison of the outgassing of samples with applied differ-
ent cleaning procedures after the PT mentioned in Section 2.4 has
shown no essential influence of the cleaning procedures. All sur-
faces could sufficiently be cleaned with cleaner and cloth. The cryo
blasting can improve the results, but the surfaces may become wet
due to condensation of humidity after extensive surface cooling by
the cryo blasting. The samples have to be dried afterwards.
3.2. Mass spectra at higher temperatures
After the PT well cleaned samples, which do not outgas at room
temperature, show a different behavior at increased temperature.
Already at 40 ◦C these samples start to outgas strongly. This effect
continues with a further increase of the temperature. Nevertheless,
after 3–4 h of bake-out at 150 ◦C the pollutions have disappeared,
even at samples with normally unacceptable PT indications like at
the sample nos. 7 and 8. Even so the temperature ofthe samples did
not reach 150 ◦C applied to the chamber wall, the cleaning process
was sufficient. Fig. 6 shows the mass spectra of the sample no. 7 at
a temperature of the vacuum chamber of 150 ◦C immediately after
the achievement of this temperature and after 4 h baking-out at
150 ◦C.