f aem - 22 jan 07 separator spark history ron moore fermilab – tevatron dept

AEM - 22 Jan 07

f Separator Spark History

Ron Moore

Fermilab – Tevatron Dept.

AEM - 22 Jan 07R. Moore - FNAL 2

f Overview

• Separator sparks can cause emittance growth and quenches via momentary orbit distortions

– Beam separation decreases– Beam kicked into collimators

• History in HEP shots/stores since Nov 02

• Based on spark counters – Confirmed with other effects: Schottky noise, emittance blow-up, vacuum in

separator after spark

• Two groups– Flattop/squeeze: B17H and C17V run hardest– When colliding: everything else

• Click on link for Spark History on Tev Web Site

http://www-bdnew.fnal.gov/tevatron/projects/HelixAndSeparators/tevatron_separator_spark_history.htm


f Separator Station Locations

• 27 separator modules – all stations have polarity switches

• B17 & C17 run hardest near flattop and in squeeze (120 kV/plate → 48 kV/cm)

• Units around IPs & D17 run hardest for collisions (≈100 kV/plate → 40 kV/cm)

Horizontal # modules Vertical # modules

A17 1 A17 1

A49 1 A49 2

B11 2 B11 1

B17 4 B48 1

C17 4

C49 1 C49 2

D11 2 D11 1

D48 1 D17 2

Separator Sparks in HEP Shots/Stores

71 entries21 “store-killers”

Thicker lines sparks occurring closer together

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f B17H/C17V

• Run hardest on ramp and in squeeze

• No B17H-1, C17V-2, C17V-3 sparks

• C17V-1 most often– Shot 4084 quench

• Fewer sparks since Jan 05 –

stopped ramping on pbar helix

• B17H-2 HEP spark 12/22/06– Mistakenly on pbar helix @

flattop for short period before shot-setup

B17H-2 minus 2491 04/28/03 120 Ramp

B17H-4 both 3048 11/25/03 115 500 GeV

B17H-4 both 3053 11/29/03 120 Early in Squeeze

B17H-2 plus 3464 05/03/04 120 980 GeV

B17H-3 plus 3829 12/09/04 120 980 GeV

B17H-3 plus 3834 12/10/04 120 980 GeV

B17H-2 plus 4586 01/09/06 120 980 GeV (cogging)

B17H-2 plus 5113 12/08/06 120 980 GeV (before cog)

B17H-2 both 5143 12/22/06 58 HEP

B17H-2 plus 5160 01/02/07 120 LBSEQ=6

C17V-4 minus 2507 05/04/03 > 100 Ramp

C17V-1 plus 2694 06/17/03 120 Ramp

C17V-4 minus 3080 12/04/03 120 Early in Squeeze

C17V-1 plus 3157 01/13/04 120 800 GeV

C17V-1 plus 3263 02/29/04 120 840 GeV

C17V-1 plus 3234 04/22/04 120 900 GeV

C17V-1 plus 3554 06/02/04 120 900 GeV

C17V-1 plus 3639 07/09/04 120 900 GeV

C17V-1 plus 4084 04/08/05 120 Squeeze, LBSEQ 7


f B17H / C17V

B17H/C17V Sparks in HEP Shots/Stores

Shu

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Fewer sparks since Jan 05 – stopped ramping on pbar helix


f Dec 04 Startup

• During shutdown, polarity switches installed on all separators; C49/D11 aligned?

• After rash of sparks (trying larger helix) from normally OK seps (C49, D11), did another round of conditioning – some in wrong polarity - sparked next store

• This explains why we avoid changing polarities without reconditioning time

D11H-2 minus 3821 12/07/04 106 ScrapingD11H-1 minus 3821 12/07/04 106 HEP

C49V-1 minus 3821 12/07/04 103 HEP

A49V-1 minus 3824 12/08/04 110 HEPD11H-1 minus 3824 12/08/04 106 HEPD11V-1 minus 3824 12/08/04 110 HEP

B17H-3 plus 3829 12/09/04 120 980 GeVB17H-3 plus 3834 12/10/04 120 980 GeV

B11V-1 both 3841 12/13/04 110 HEP

B11H-1 both 3854 12/18/04 108 HEP

C49V-1 minus 3968 02/05/05 95 ScrapingConditioning + Reduction of collision helix by 10% 12/19/04

shutdown 8/26/04 - 12/7/04

Conditioning 12/9/04 (B17H in "wrong" polarity; collision, not injection helix)

Conditioning 12/12/04 (B17H in correct polarity for injection helix, B11V in wrong polarity for HEP for 6 hrs)

Conditioning 12/13/04 (B11H and B11V spent some time in wrong polarity for HEP)


f B11H/V

• 13 incidents–11 “store killers”

• Note clumps…

• Spring 04 & Dec 04–Trying larger collision helix

–Start-up after 2004 shutdown

• Nov-Dec 05–B11 separator RGA leak

higher cold beam tube + separator vacuum

–Store 4515 spark led to B17 spool piece failure

–Leaky feed-through replaced

B11H-1 both 2443 04/19/03 15-90? Init Collisions

B11H-1 both 3048 11/25/03 85 HEP

B11H-1 both 3446 04/27/04 105 Initiate Collisions

B11H-1 both 3629 07/08/04 105 HEP

B11H-1 both 3854 12/18/04 108 HEP

B11H-1 both 4508 11/19/05 100 HEP

B11H-1 both 4515 11/21/05 100 HEP

B11H-1 both 4549 12/14/05 100 HEP

B11H-2 both 4990 09/30/06 100 HEP

B11H-2 both 5055 11/09/06 100 HEP

B11V-1 both 3341 04/02/04 110 HEP

B11V-1 both 3841 12/13/04 110 HEP

B11V-1 both 4374 09/08/05 98 HEP


f A49H/V

• A49V sparks when trying larger collision helix (Dec 04, spring 05) led us to replace A49 separators with better conditioned ones in 2006

• New A49H-1 sparked 3 times soon after start-up…OK for few months

• Have not tried increasing voltage / enlarging helix since then

A49H-1 both 2928 08/20/03 88 HEP

A49H-1 minus 4745 06/09/06 100 Before scraping

A49H-1 minus 4889 08/06/06 100 HEP

A49H-1 minus 4893 08/07/06 50-100? Initiate Collisions

A49V-1 both 2013 11/28/02 85 Init Collisions

A49V-1 minus 3824 12/08/04 110 HEP

A49V-1 both 4053 03/21/05 110 HEP

A49V-2 both 4078 04/06/05 110 HEP

A49V-1 both 4151 05/18/05 110 HEP

9 incidents

5 quenches

1 BIG emittance jump rendering store useless


f D17V

• D17V likely “contaminated” in October D32-5 failure - electrical arc through beam pipe much of D sector had terrible vacuum for some time

• Sparked at low operating voltages, little impact on beam (fortunately)

• D17V was conditioned extensively during shutdown and subsequent E39 cryo leak repair

• Has finally settled down – no sparks in 2 months (insert kiss of death here)

D17V-1 minus 5019 10/23/06 64 Squeeze, LBSEQ 24

D17V-1 minus 5019 10/23/06 53 HEP

D17V-1 minus 5030 10/26/06 53 During scraping

D17V-1 both 5030 10/26/06 53 HEP

D17V-1 minus 5052 11/07/06 53 HEP

D17V-1 minus 5065 11/13/06 53 HEP

D17V-1 minus 5074 11/16/06 53 HEP


f Summary

• 71 spark incidents in HEP operation in ≈4 years– Nearly 1/3 were “store-killers” = quenches or big lumi drop

– ≈40% were “self-inflicted” = higher voltages, poor vacuum, after conditioning in wrong polarity

• B17H and C17V separators spark less frequently up ramp/at flattop since stopping ramping on pbar helix (≈Jan 2005)

• Running with poor separator vacuum is not a good idea– See B11 incidents in Nov 05

– Take time to fix the problem right

• Be careful trying larger voltages and changing polarities– Don’t want store-killers becoming Tevatron-killers (avoid quenches)


f

HV Electrode feedthru

Titanium Sublimation Pump

Flexible Support

Rigid Support

Heater

Ion Pump

Tevatron Electrostatic Separator Components

This is a horizontal separator……insulating blankets not shown


f Others

• 4 “store-killers”

• C49 mainly negative only

• D11 all but one during Dec 04 startup with larger helix

B48V-1 both 4950 09/12/06 75 HEP

C49V-1 minus 2285 02/28/03 95 HEP

C49V-2 minus 2341 03/23/03 95 Scraping

C49V-1 minus 3821 12/07/04 103 HEP



C49V-1 both 4210 06/17/05 95 Scraping

C49V-2 minus 4828 07/14/06 100 During scraping

D11H-1 minus 3821 12/07/04 106 HEP

D11H-2 minus 3821 12/07/04 106 Scraping

D11H-1 minus 3824 12/08/04 106 HEP

D11H-2 both 4554 12/18/05 85 HEP

D11V-1 minus 3824 12/08/04 110 HEP

f aem - 22 jan 07 separator spark history ron moore fermilab – tevatron dept

Documents

shutdown slide

pbar helix slide

sparks c17v

d481d172 slide

replaced slide

setup slide

moore fnal7

spark incidents