It's a good catch.
That's how our team works !!!
I'm glad, this is not the HVPS yet and we
still have some time (!)
to find a schedule window to
clean them inside and
install somehow the dust filters
into the HVPS section
of both cabs HV1 and HV2 .
Dear Gary and Mike, please, give
your opinion, what kind of filters
you would recommend to use.
Thanks in advance
Sincerely
Anatoly
Brendan Kiburg wrote:
Dear Colleagues,
This morning we discussed with the hallendienst our plans. They
explained that due to time constraint, we should not first look in the
top/down access ports, but rather we should move or wait until Monday. We
decided to move and they disconnected the kicker.As the upstream bellow was removed, the SU identified that the
collimator was no longer in position. He said that it was at already at
an angle relative to vertical (~45 degrees), and that it fell
further when they removed the bellows.Based on what the SU told us, we fully believe the collimator
was in electrical contact with the upstream deflector plate and the
beampipe at the time of opening. We remeasured the resistance between the
fischer connector in HV1 and ground and obtained >20 MOhm , so the short
appeared to be gone. At air, we reconnected the power and ground and
turned on HV2 as a control in the fixed frequency mode. We
then ramped up the voltage on HV1 and found no breakdown and we were able
to achieve +9 kV on HV2 and -9 kV on HV1. We note that
there was no Red LED on card 13, but we concluded yesterday this is a
problem with the optical fiber and not a problem related to the
breakdown. This was our reasoning for stopping at 9 kV for the time
being.As a result of our findings, we believe there is clear evidence the
collimator was responsible for the breakdown. We have removed the
collimator, as there was damage to the nylon ends inserted in the set
screws. We made the working decision to return to vacuum without
inserting the collimator, but we have left open the option of reinserting
it as early as next wednesday if we see significant evidence that we need
it for beam quality.We are currently pumping the beamline, which will take on the order of 8
hours. We can then verify that everything still works, and continue with
our measurement program. If there are any further problems, we will
communicate them to all of you. We will send another email later tonight
when we have verified the repair was succesful. Thanks for all the
efforts and communication; we appreciate it.With guarded optimism,
Brendan and Peter