# Presentation: 143763

## Conditioning tests

** **
**    ****Separator history**
**    ****Conditioning at 150 – 180 kV**
**    ****Dark currents**
**    ****Spark rate at 170 kV**
**    ****Radiation scans**
**    ****Summary**

**Reconditioning Tests  for Separator # 20 **

## Measurement Scheme

## Separator History

-      Separator (vertical) with hand-polished SS plates was constructed in 1990?
-       Removed from Tevatron in March 2006
-       Reassembled  and cleaned in June 2006 (mounted 2 new HV feedthrus)
-       _Reconditioned at voltages up to 180 kV in June - July, 2006  at MP-9_

**Separator History**

## Conditioning at 150 kV (June  6-7, 2006)

**Conditioning at 150 kV (June  6-7, 2006)**

**Negative Polarity **

**Positive Polarity **

- ~ 15 sparks

- ~ 100 sparks

## Radiation scan at 150 kV (June 7, 2006)

- Hot spot

- Microdischarges

## Conditioning at 170 kV (June 7, 2006)

**Conditioning at 170 kV (June 7, 2006)**

**Negative Polarity **

**Positive Polarity **

- ~ 20 sparks

- ~ 40 sparks

- Voltage drop

- High current

- _Problems: _
-      - no current drop for about 8 hours
-      - voltage is limited by current limits (100 A)

## Conditioning at 160 - 170  kV (June 8 - 9, 2006)

**Positive Polarity **

**Conditioning at 160 - 170  kV (June 8 - 9, 2006)**

- ~ 30 sparks

- ~ 20 sparks

- June 8

- June 9

## Conditioning at 170 - 180  kV (June 10 - 11, 2006)

- ~ 220 sparks

**Positive Polarity (June 10)**** **

- 80 sparks

**Conditioning at 170 - 180  kV (June 10 - 11, 2006)**

## Radiation scan at 165 kV (June 11, 2006)

**Radiation scan at 165 kV (June 11, 2006)**

- Hot spot

## Spark Rate Measurements

**Spark Rate Measurements**

**Negative Polarity **

**Positive Polarity **

## Radiation scan at 165 kV (July 12, 2006)

- Radiation hot spots are  suited in the central separator area for both polarities

- Hot spots

- Hot spots

## Dark Current  Measurements 

**After conditioning at 150 kV**

**After conditioning at 180 kV**

**Final dark currents (2 weeks conditioning at 170 kV)**

**Dark current after shut down (June 15 - 28)**

- Current at 170 kV is about 30 A
- for both polarities

- After conditioning at 180 kV a current has dropped for negative polarity at 150 kV from 40 A to 5 A

## Spark Rate Measurements

**Spark rate at 170 kV: **
**      ****~  1.5 sparks/day for negative polarity**
**      ****~  2.5 sparks/day for positive polarity**
** ****Estimated spark rate at 150 kV:       **
**      ****~ 10 sparks/year  for both polarities**

## Summary

_**The results of conditioning tests (June 6 – July 12, 2006):**_
-     The separator # 20 removed from Tevatron was reconditioned at voltages up to 180 kV
-         for both polarities.  The higher conditioning voltages helped to eliminate a high corona
-         current observed at 150 kV and improve spark rate parameters.
-     Parameters at 170 kV:
-             -  dark current is ~ 30 A (not change for about one month)
-             -  spark rate  is about  2.5 spark/day for both polarities
-     Separator parameters at 150 kV:
-             -  dark current is about 8 A
-             -  estimated spark rate is about 10 sparks/year
-     Radiation scans carried out a few times have detected hot spots in the central area.
-     No vacuum leak was detected before starting of the conditioning tests but we could not
-        reach vacuum better than 10 -9 torr.  A separator was opened and stored for long time
-        without HV  feedthrus so  we need to bake out before operation at Tevatron.
- Separator #20 has spark rate roughly 10 time higher in compare with regular new separators conditioned at 180 kV  but parameters are still good so we could use one as spare unit for replacement of the Tevatron separators.