Task:
We performed vacuum leak test for IMC requested by Uchiyama-san.
And we found serious vacuum leaks at MCF.
Summaries of the vacuum leak test for IMC on 31 are as follows;
1. Helium leak with level of 1.0 x 10^-8 Pam^3/s at hermetic D-sub connector flange.
The leaked hermetic seal D-sub connector is difficult to repair.
It must be replaced with a new flange with a new hermetic seal D-sub connector.
2. Helium leak with level of 1.0 x 10^-9 Pam^3/s at laser beam port from PSL.
3. Helium leak with level of 1.0 x 10^-9 Pam^3/s at K-400 blank flange.
4. Cone bellow at the foot of the MCF tank.
Please see attached photos.
The leak level of the cone bellow was around 1 x 10^-9 Pam^3/s.
B.G. was 5.7 x 10^-10 Pam^3/s.
After splaying small amount of helium gas around the cone bellow,
the indictor of LD was changed from 5.7 x 10^-10 Pam^3/s to 1.3 x 10^-9 Pam^3/s.