Further testing media were not tested.
2.4. Cleaning processes after PT
After the PT execution the samples were cleaned with the fol-
lowing procedures respectively:
A) cleaner U87 and cloth, cryo blasting with CO2, drying with hot
air, ethanol
B) cleaner U87 and cloth, drying in the air and
C) in between cleaning after the penetration process with cleaner
U87 and cloth (in this case without the later application of the
developer) – thereby typically remains of the penetrant stay on
the surface, especially at rough surfaces.
It is expected that the cleaning effect is most efficient with pro-
cedure (A) and is the worst with (C).
2.5. Test rig
A schematic of the vacuum chamber and equipment is shown
in Fig. 3.
The test chamber could be baked withheating bands which were
placed on the outside of the vacuum chamber. The temperature of
150 ◦C is the standard bake-out temperature to be applied for the
UHV components at W7-X. The heat was mostly transferred to the
sample by thermal radiation. So the samples were not as hot as the
chamber wall set to 150 ◦C.
3. Results and interpretation
3.1. Mass spectra at room temperature
To show the basically negative influence of the penetrant to the
vacuum environment, the sample no. 8 was investigated in the
mass spectrometer after a particular insufficient cleaning proce-
dure whereby rests ofthe penetrant were clearly visible. The typical
fragments of hydrocarbons at mass numbers between 45 and 100
are clearly visible, see Fig. 4.