RE: Kicker grading measurement

Peter,

Please find attached your photos with comments.

1) Scope.jpg: it is not clear to me whether the probe cable passes through the ferrite 2 or 3 times. However 2 of the times are in opposite directions (I believe) and therefore these turns will cancel magnetically: the cable must always go through the ferrite from the same side.

2) Ground.jpg: the ground wire from the probe goes close to both the conductor carrying return current from the stack as well as the HV conductor. Please arrange for the probe ground wire to be reasonable distant from conductors carrying pulse current (while still attaching near to the central ground).

3) probe.jpg: the probe, as shown, will be strongly capacitively coupled to the stack and will therefore pick up a lot of noise. Please hold the probe at right angles to the stack.

Others

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A) When you measure the voltage of a card, are you ensuring that the probe is DIRECTLY touching either the drain or source connection of the card of interest? (the probe should not be at the other end of the short wire that connects different cards, as this wire carries pulse current).

B) As per Francoise's suggestion, it would be a good idea to average a measurement, e.g. 25 times, to reduce background noise.

C) Please confirm your numbering system: is "1" at the DC or pulse end of the stack? (we consider "1" to be the DC end).

D) As far as reasonably possible keep the probe ground wire close to the side of the cabinet, as this will minimize induced currents.

Cheers,

Mike

From: Peter Winter [mailto:peter.winter@psi.ch]
Sent: Wednesday, May 03, 2006 2:28 AM
To: Peter Winter
Cc: Mike Barnes; Mulhauser Francoise; kiburg@npl.uiuc.edu; kammel@npl.uiuc.edu
Subject: Re: Kicker grading measurement

Sorry, in the first attempt the pictures were not send since I didn't send the email in HTML format. Once again:

I put together some pictures.
The following two pictures (which have to be rotated by +90 and -90 degree, respectively) showour ground cable for the HV probe connected inside the cabinet. The length is around 30-40cm.

And that's the HV cable connected to the oscilloscope:

Finally, here's how we measure:

Since we are expecting beam tomorrow, we prepared the kicker to be in kicking mode. During the next beam off time, we'll continue the measurements, repeat the series for one card and see how it changes (although we already did that and the results are quite stable).
Greetings
Peter