sPHENIX discussion of the superconducting solenoid

["Yip, Kin" <kinyip AT bnl.gov>]

Hello Ray,

Could you please find a time to open  the doghouse attached directly to the Magnet Coil/Cryostat after you come back from your vacation ?

As you can see below, Carl (and I) went to check on it today and didn't make any breakthrough.  We'd like to check the doghouse
and even if we cannot fix anything after you open it, we'd at least like to make a new voltage-tap-connection for the problematic
VT-11 (and also for VT5) , as a spare (or replacement).  Now, it's the better time to do it as we have all the platforms/staircases etc.

Kin

-------- Forwarded Message --------

Subject:	Opening the sPhenix inner doghouse
Date:	Wed, 20 Feb 2019 11:14:37 -0500
From:	Schultheiss, Carl <carls AT bnl.gov>
To:	Yip, Kin <kinyip AT bnl.gov>, Mills, James A <mills AT bnl.gov>, Joshi, Piyush <joshi AT bnl.gov>

Hi,

 

   During the high current test two voltage taps (VT10 and VT11)

were intermittent. VT11 first opened during cool-down before

the magnet was powered. VT10 opened during testing. At the

time the VTs were checked with an ohm-meter at the interface

rack and were found to be open. During warm-up the VTs reconnected.

   Today, Kin Yip and I examined VT 10 and VT11 inside the

sPhenix outer doghouse. We measured the resistance

between the VT wires, they measured 400 Ohms. This means

they are connected now.

   I recommend we open the inner doghouse to further examine

the VTs and the resistor board inside the inner doghouse. VT11

is at the joint between the magnet lead and the extension. This

VT will be accessible. I recommend we run a redundant VT for this

side of the joint; we have spare pins, and resistors at the outer doghouse.

We should also run a redundant VT for VT5, which will also be accessible

if we open the inner doghouse. VT10 is the tap for the inner magnet coil

and negative magnet lead. VT10 is more problematic, it runs inside

the cryostat and will not be accessible. If nothing is obvious it makes it

more important we have additional redundant VTs in case VT10 opens again.

We can then reconfigure the quench detector easily, using the redundant

VT11, and have almost the same level of protection we have when VT10

is good.

 

 

Carl Schultheiss

Principal Electrical Engineer

Collider-Accelerator Department

Brookhaven National Laboratory