Re: Kicker test Nr 2

[Brendan Kiburg <kiburg@npl.uiuc.edu>]

Dear Mike and Gary,
  First let me clarify that currently we are running with 2 plates out of
4, that is, just the +HV.  The HV1 fischer connector is connected as
usual, and there is no demand voltage for HV1 or MV1.  I believe this is
the grounding that Gary pointed out in the most recent email.

 Our plan for Thursday is to try and clean the HV1 "faulty" fischer
connector and look in more detail for any tracks.  Barring success, we
will then use the idea to run with 3 out of 4 plates connected.  To
accomplish this, I just want to make sure that I understand the
differences from normal operating conditions.

1) We have to remove the 2.5kR resistors from HV1 (Mike's email)
2) We have to remove the fischer connector from HV1 (Gary's email)
   (as opposed to the situation now where we have HV1 grounded via the
fischer?)

3) We will observe a reduced current on HV1 relative to HV2 because of the
difference in the load

4) I spoke to Francoise and got the impression that the display on the
main power on the MV1 cabinet which normally reads 315V and 1.354 mA might
be reduced as well.  Could you please verify what this display should read
in the 3 plate mode?

Finally, we plan to run with a fixed frequency kick signal (5 microseconds
at 1 kHz) during this switch to provide a known operating
condition.  Furthermore this will provide us with the ability to compare
the currents on HV1 and HV2 and identify the load difference.  After it
is operating in this state, we would switch to the muon on request mode
for data taking.

We'll wait for confirmation before proceeding with this change.  Thanks
for all of your help.

Best regards,

Brendan




On Wed, 30 Nov 2005, Gary Wait wrote:

> Brendan
> If you are running with only the +HV then I suggest that you connect the 
> negative plate in HV1 to ground via the "faulty" fischer connector
> so that it does not charge up and give you a varying deflection. You 
> should be able to run with the neg plate in the MV1 cabinet at negative 
> voltage as long as the HV1 fischer connector is disconnected and this 
> will give you a bit more deflection.
> Regards
> Gary
> 
>  
> Brendan Kiburg wrote:
> 
> >Dear colleagues,
> >  Thank you for the various suggestions as to how to proceed.  Let me
> >start by summarizing the options, as we see them here. 
> >
> >1) Try to clean the connection from the cabinet side and see if there is
> >anything obvious in the connector.  We can also investigate the optic
> >fiber at this point and try to get the RED LED functional again.
> >
> >2) Remove the kicker from the area to produce a suitable workspace and
> >connect the HV1 kicker plate to the MV1 kicker plate as suggested
> >in Dave's email.  We would then  disconnect the HV1 plate from the 
> >"Fischer" connector and ensure that no other short circuits exist in
> >the pipe or on the pipe side of the socket.  If the breakdown was caused
> >by the plug or socket this will work.  If the probelm lies in the
> >deflector plates, this will not work.
> >
> >3) Run with only 1 kicker plate for now in muon on request mode and take
> >further actions at a later appropriate time.
> >
> >
> >We are currently runing in the muon on request mode with only the positive
> >plate which results in a weaker kick.  We have observed that our
> >extinction factor has been reduced by roughly a factor of 3 with the loss
> >of the negative plate.  While this is a problem, we may potentially be
> >able to continue running in this mode and collect useful data.  
> >
> >  Since we must proceed with understanding the cause of the problem as
> >well, I suggest that Thursday Peter and I will take some amount of time to
> >implement step 1 and try to finalize our belief that the problem is inside
> >the pipe. If we cannot solve/identify the problem with the cleaning and
> >examination of the connector/socket, then we should make some decisions
> >about extracting the kicker for Dave's proposed conversion and continuing
> >with the mucap run.
> >
> >Best regards,
> >
> >Brendan
> >
> >On Wed, 30 Nov 2005, Mulhauser Francoise wrote:
> >
> >  
> >
> >> Hello every one,
> >>
> >>I don't know  where to start to be clear and efficient.
> >>
> >>The problem lies between the "fischer" connector, the beampipe, the cupper braid (inside the tank, between the wall and deflector plate) and the plate, all for the HV1 cabinet.
> >>
> >>1 To do what Dave suggests, or what Gary suggests, or what Mike suggests requires to open the tank. The easy access is via the middle top or bottom flanges. When I mean easy, it is a way of speaking. Ask Rob about his "pipe riding" and I can tell you a lot about "under pipe" scrowling. You have ABSOLUTELY no visual or physical access to the cupper braid inside the beampipe without removing the kicker from the beam pipe. It is an important work.
> >>Therefore, any changes inside the beampipe will require to take the kicker out and work outside the area. (Obviously, you have to first close manually the valve between the separtor and the kicker. Peter, you remember that I showed you how to do it. The screwdriver should still be in place! Don't forget that step)
> >>
> >>If you have to de-solder the cupper braid, you have to use the "big" solder iron. On the deflector plate side, the braid is inserted inside a ball. It stays in place via a allenkey screw. Use the mirror to help you reaching it. I would recommend to remove the screw first, before de-soldering. Secondly, this is again a "pain in ..." job, because you need to heat the connection on the beampipe side. It takes a while. The HV1 side was beautifully made by Anatoly, so you will have a good amount of solder inside, well spread. My suggestion, if you reach this step, would be to try to bend that braid once removed from the deflector plate and to make test in this position, to avoid the de-soldering job.
> >>
> >>
> >>2. The faulty location is at HV1, namely at one of the place where the HV power supply is located. If one would clip the deflector plates, we would not be in the same condition as last year. However, Mike and Gary may say that it is not a big problem to remove both of the 2.5kOhm resistor in the HV1 and to run the negative side with only MV1. 
> >>
> >>3. To reach the electronics of the kicker, you need to remove the metalic "floor" of the RF part of the cabinet. Unfortunatelly, the kickerr location is such that you CAN NOT open a door fully. Thus, you will ahve to remove the door (toward the magnet) from the hinges (don't remember the real english name: the stuff which allow a door to rotate on an axis). Then you can access the plate. To find the correct location of the fiber optic for DN13, you will have to follow the fiber themselves and use the special tool to remove the fiber from the board. 
> >>
> >>We can discuss some issue. You can look at my webpages about the kicker 
> >>http://www.npl.uiuc.edu/~mulhauser/mulan/kicker/.... to see some picture of the various parts.
> >>
> >>I would suggest, if Mike is available tomorrow, to give him a ring and discuss the options lively.
> >>
> >>Good luck and best regards
> >>Francoise
> >>
> >>-----Original Message-----
> >>From: Michael Barnes
> >>To: Gary Wait
> >>Cc: Peter Winter; Michael Barnes; kiburg@npl.uiuc.edu; Mulhauser Francoise; kammel@npl.uiuc.edu; hertzog@uiuc.edu; michael.barnes@triumf.ca; Robert M Carey; Anatoly Gafarov; rmcnabb@uiuc.edu
> >>Sent: 11/30/05 8:52 PM
> >>Subject: Re: Kicker test Nr 2
> >>
> >>Hi all,
> >>
> >>Sorry I have been in meetings etc all afternoon so just getting around
> >>to
> >>reading email. It is good that you confirmed the general area of the
> >>breakdown. Dave's suggestion may, or may not, work depending on the site
> >>of the breakdown --- e.g. if there is a problem with one of the support
> >>HV1 plate ceramics it will not work. However I suspect the most likely
> >>place for the failure is the Fischer connector. Or maybe it is something
> >>as simple as the internal connection (wire) from the plug to the HV1
> >>plate
> >>breaking and dropping down close to the beam pipe. If you have access to
> >>the beam pipe this would be easy to check. In addition, if there is
> >>nothing obvious in the beam pipe, I would suggest disconnecting the wire
> >>from the Fischer socket (inside the beam pipe). Then repeat the HV test,
> >>with the Fischer plug plugged into the socket. If there is breakdown, it
> >>is the plug or socket; if there is no breakdown, the problem lies with
> >>the
> >>deflector plates e.g. support ceramics).
> >>
> >>Good luck
> >>Mike
> >>
> >>    
> >>
> >>>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
> >>>>
> >>>>        
> >>>>
> >>>Brendan and Peter
> >>>Card dn-13 is likely not getting light from the fiber optics. In order
> >>>to turn off a card (and thus get a red led on) there must be light on
> >>>from the fiber optic cable. A quick check on this would be to
> >>>interchange the fiber optics cables between cards dn12 and dn13 and
> >>>apply HV with the fischer connector disconnected. You will likely see
> >>>that the red LED on card dn 12 will not turn on. You will  need to
> >>>      
> >>>
> >>check
> >>    
> >>
> >>>that the faulty fiber optic cable is connected properly at both ends
> >>>      
> >>>
> >>and
> >>    
> >>
> >>>if that doesnt work then replace the fiber optic cable. If you cannot
> >>>repair this fault you will have to run at a lower voltage on HV1
> >>>cabinet. ie: 16/17*12.5kV=11.8kV to protect the remaining 16 cards in
> >>>the stack. (or see Daves email)
> >>>
> >>>RE: fischer connector.
> >>>The short circuit is either external to the tank or internal. You
> >>>      
> >>>
> >>could
> >>    
> >>
> >>>try cleaning the external connection with alcohol and see if it is
> >>>carbonized anywhere. There might be tracking along Anatolies connector
> >>>when it is plugged in, so it should be dismantled and cleaned if
> >>>possible. It that doesnt work you will have to open the tank and check
> >>>inside. The suggestion of Daves to run with the two sets of plates
> >>>coupled together is probably the best plan and you will still need to
> >>>open the tank to air. You will have to disconnect the internal
> >>>connection of the faulty plate from the fischer connector, or you will
> >>>still have a short to ground.
> >>>
> >>>Regards
> >>>Gary
> >>>
> >>>
> >>>      
> >>>
> >
> >  
> >
>