Chandra R., Gerardo M., Kyle R.. Ken D.

Today we helium leak tested the CFF joints on CP4.  With the 55 L/s ion pump valved-out and the leak detector backing the 450 L/s turbo pump (which was valved-in for this exercise), each CFF joint was sprayed with an audible flow of helium for 10s of seconds each.  The nominal helium background signal was < 2 x 10-9 Torr*L/sec during testing.  Additionally, Chandra partially filled the (now empty) inner LN2 vessel with helium via applying helium to the bottom level sensing line and allowing the displaced air to exit the upper sensing line.  This test was incomplete in that the exhaust exiting the upper level sensing line was not monitored for O2 concentration and thus the helium concentration within the inner LN2 vessel could not be determined. 

A pressure accumulation test was also done.  For this test, all pumps were valved-out and the pressure within CP4 was allowed to rise (see attached graph). 

By all indications, CP4 seems to have survived the months-long bake exercise unscathed.  Of note too was that, while being pumped by only the turbo during leak testing today, that the pressure achieved nearly the same value as had been observed just prior to the unexpected turbo shut down last Thursday. 

Ken D. is well on the way to restoring the electrical connections that had been removed to accommodate the heated enclosure.  He also reminded us to consult with him later in the week prior to operating GV11 so as to review the details pertaining to the limit switches and motor rotation etc...

Gerardo M. and I have started to re-hang the annulus ion pump plumbing on GV11.  Chandra R. intends to be ready to open GV11 as soon as EOB Friday - stay tuned.  GV12 won't be opened until later.