Re: [BLAST_SHIFTS] Shift summary 03/29/2005 C (17-1)

From: Douglas Hasell (hasell@MIT.EDU)
Date: Wed Mar 30 2005 - 08:27:30 EST


Hi,

        I suspect the problem was that L21 guard wire tripped off. Hitting
REST does not turn this back on, therefore the sense will trip almost
immediately (no guard wire "protecting" it).

        When the guard wire trips you have to go to STBY and then back to OPER.

        Lowering any sense wire HV below 3750 makes those boxes inefficient
and should not be done.

                                                                         
                      Cheers,
                                                                         
                                      Douglas

26-415 M.I.T.
Tel: +1 (617) 258-7199
77 Massachusetts Avenue Fax: +1 (617)
258-5440
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hasell@mit.edu
On Mar 30, 2005, at 1:02 AM, Electronic Log Book wrote:

> Operator: karpiusp
>
> Many WC trips on L21 sense and guard wire. This was not bad at start
> of shift but increased over time. During RUN 14761 reduced L21 to max
> voltage it would hold for more than a few minutes - this was 3700V.
> Thinking that this was too low I asked CCR if they could lower the
> injection from 210mA to 200mA to mitigate ion buildup. During the
> following run I was able to raise L21 to 3800V where it stayed for the
> remainder of the shift. - perhaps ready to try 3850V
>
> Noticed that tclr0 seemed to be dominated by self-timing events but
> this dissipated over a few hours - no idea why
>
> Took ABS RUNS:14579-14760 (L21 at 3850V)
> 14761 (L21 at 3700V)
> 14762-14765 (L21 at 3800V)
>
> VPol results for 3/28/05 C shift(latest crunched): 3.16 kC
> L: 0.519+-0.062 R:0.549+-0.042
>



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