Re: Kicker test Nr 2

["David W. Hertzog" <hertzog@uiuc.edu>]

Hello all,
    I have read quickly the blizzard of emails but it is difficult for 
me to recommend specifics regarding the actual problem.  Instead, I 
simply want to remind you of a potentially useful temporary work-around 
(if this indeed isolates the problem for a bit).  This may be useless 
for the present situatio9n, but keep it in mind in case the situation 
goes in this direction.

    As we did last year, we could imagine opening the top and port of 
the kicker vacuum chamber (in situ) and using a set of inter-connected 
alligator clips ... I used 6 in total ... to bridge the front and back 
plates into operation by only 2 of 4 kickers.  Then, disconnect the 
troublesome units ...unplug the fisher entirely.  You should then be 
able to run the thing with just 2 kickers going at the price of a bit 
longer rise time / fall time.  It might get you through the next couple 
weeks or until we have a chance to make a more complicated repair.

    Dave

Peter Winter wrote:

> Hi all,
>
> we just performed the test Francoise proposed by removing the fisher 
> plug inside cabinet HV1.
>
> Our test included the following steps:
> 1) Switching to a constant high TTL level (DC mode from endless gate 
> generator)
> 2) Ramping HV2 to see that all red LEDs are ok at 5kV with fisher plug 
> still inside. That confirmed that we have a high TTL
> 3) We removed the fisher plug and taped it in a safe position on the 
> plastic shelf far away any metal.
>     - ramping HV2 to 5kV with lower red LEDs ok, the upper were not 
> lightened due to DC mode
>     - ramping HV1 without current drawn to 5kV on negative polarity, 
> upper red LEDs turned on, no red LED on bottom stack due to DC
> 4) We then decided to go to the kicking mode (5mus on at 1kHz) in 
> order to also see the red LEDs on the lower stack of cards in HV1.
>     - ramping HV2 to 5kV with all red LEDs ok (top ones bright, lower 
> faint)
>     - ramping HV1 to 2.4kV with 001mA, we observed that the red LED on 
> the card DN-13 had NO red light, while all others were on
> 5) We reconnected the fisher plug with DC mode:
>    - HV2 ok when ramping up
>    - HV1 has immediately a rising current of several mA
>
> Summarizing:
> - It seems that the breakdown is somewhere between the fisher plug and 
> the plate
> - The card DN-13 still has no red light. Since this is en exchanged 
> card, could the problem be connected with the optic fibre?
> - When we first saw this breakdown we could go up twice to 2kV with no 
> current. Only when the breakdown occured the current remained. Now the 
> situation changed and we immediately see the breakdown current. Does 
> that mean that the breakdown point worsened and became permanent.
>
> Waiting for new proposals and conclusions
> Brendan and Peter