BPM UpgradeBPM Upgrade

Presented by: Nadine Kurita

Contributors: S. Smith, S. Ecklund, J. Sebek, D. Martin, R. Hettel, R. Johnson, N. Reeck, M. Kosovsky, D. Arnett

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OutlineOutline

BPM Upgrade project overview 2005 upgrade/testing LER Arc BPM’s IR2 BPM’s Summary

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BPM Upgrade OverviewBPM Upgrade Overview

There are 3 styles of BPM’s in the PEP-II machine. LER Arc BPM’s

Helicoflex sealed, SS housing HER Arc BPM’s

Welded, CuNi housing LER/HER Straight BPM’s

Welded, SS housing

Thermal and experimental models show that the BPM buttons could be approaching temperatures around 800 to 1000 C from HOM heating.

HOM heating has numerous parameters (i.e. bunch current, total current, beam position, chamber geometry).

Two areas are of major concern due to the high current and BPM position relative to beam.

LER arc BPM’s IR2 BPM’s

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Current Upgrades - 2005 Downtime (cont.)Current Upgrades - 2005 Downtime (cont.)

Four sets of modified LER Arc BPM’s at ARC 1,

Goal – to reduce HOM power. 7 mm molybdenum button

Welded tabs on buttons and pressed them off.

50-150 lbs, average was ~ 60 lbs (excluding

outliers).

Pressed molybdenum buttons 100-600 lbs Test push ~850 lbs leak tight.

One set has a 5 mm gap between button and housing.

One set has a 1 mm gap between button and housing.

Laser welded SS insert

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Current Upgrades - 2005 Downtime (cont.)Current Upgrades - 2005 Downtime (cont.)

7mm button reduces power dissipated and transmitted by the BPM’s. (S. Ecklund)

Factor of 2 – 4? Data indicate that the 7mm button with the 1mm gap

absorbs the least amount of power. Shorted button to housing

3 mm wide x 6.3 mm long, .4 mm thick Inconel strip resistance welded 0.25 mm of copper for thermal conductivity.

T increase by ~ 23 X For, Q = 10W, T = 200C

Issues Overheated the attenuators that were added for the

additional HOM power that would be coming out of the transmission line.

Resistance welds may fail and lead to arcing.

Does not appear to be a viable solution.

short

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2006 LER Arc BPM Upgrade2006 LER Arc BPM Upgrade

Option 1 – Retrofit existing Borosilicate Glass BPM’s. Successfully completed this downtime. 7mm button reduces power dissipated and transmitted. Signal meets precision/accuracy requirements for stored beam

at high current. Signal is sufficient for single turn high current beam. Downtime experience

Welded tabs on buttons and pressed them off. 50-150 lbs, average was ~ 60 lbs (excluding outliers).

Pressed molybdenum buttons 100-600 lbs Test push ~850 lbs leak tight.

Pin diameter tolerance +/-.002” Press fit tolerance is +/-.0001” Pins were measured and buttons were match machined – forces

were still larger than anticipated. Errors in QC data lead to failures. Button partially pressed on. Fit tolerance on small diameters make this task difficult & costly.

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Design – BPM RetrofitDesign – BPM Retrofit

Current Plan Re-design press fit to reduce force and increase tolerance band.

Taper and reduce press fit region. Pros

Does not require significant design effort. Cons

Requires manufacturing downtime work. Could encounter difficulties and failures

Buttons diffusion welded from high temperatures? Glass seal failing from removing buttons or pressing buttons (low risk – from tests). Partially pressed on buttons – difficult to recover BPM if this occurs. Thermal conductivity – 8 to 20 X worse than alumina. Contingency cost could run higher (SLAC labor versus fixed cost).

Cost Estimate (N. Reeck) – consistent with AIP budget Retrofit of the BPM

Indirect Cost: $339.65 each including 28% contingency Installation

Indirect Cost: $168 each Cost does not include helicoflex seal

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Design – Alumina BPMDesign – Alumina BPM

Option 2 Saint Gobain Feedthru SSRL/SPEAR3 – working on purchasing these for a small gap undulator chamber. Preliminary cost estimate $245 each for 20 pieces. Bake out/leak check - +$60 each. Specification and drawings near completion 90%. Pros

design exists Alumina – better thermal conductivity Cost is competitive with retrofitting.

New - $305, does not include destructive & electrical testing cost. Total cost within AIP budget – potential less risk of overrun due to fix cost. Retrofit - $340

Cons Needs testing Dielectric constant 2 X higher than glass. New vendor – not much reliability data. Not electrically equivalent to remaining BPMs Schedule

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Alumina Feedthru Layout DrawingAlumina Feedthru Layout Drawing

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Major Milestones – option 1 - RetrofitMajor Milestones – option 1 - Retrofit

Dec ’05 - Complete scope of project – critical decision. Jan ’05 - Complete new design Feb ‘05 - Push pull tests Mar ‘06- Order Parts May ’06- Receive buttons Aug ’06 - Remove & modify 200 feedthrus,

2-3 people/month Sep ’06 - Remove & modify 200 feedthrus Oct ’06 - Remove & modify 200 feedthrus Nov ’06 - Remove & modify 200 feedthrus Dec ’06 - Complete re-installation

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Major Milestones – option 2Major Milestones – option 2

Dec ’05 - Complete scope of project – critical decision. Dec ’05 - Complete design specification Dec ‘05 - Order Prototype Feb ‘06 - MAFIA/RF simulations Mar ’06- Receive Prototypes May ‘06- Destructively test May ‘06- Order production units Aug ‘06 - Receive 1st lot (100 units) Nov ’06 - Receive last lot (200 units/month?) Sep ’06 - Install 1st lot Dec ’06 - Install last lot

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Major MilestonesMajor Milestones

Dec ’05 - Complete scope of project. Dec ’05 - Complete design specification Dec ‘05 - Order Prototype Feb ‘06 - MAFIA/RF simulations Mar ’06- Receive Prototypes May ‘06- Destructively test May ‘06- Order production units Aug ‘06 - Receive 1st lot (100 units) Nov ’06 - Receive last lot (200 units/month?) Sep ’06 - Install 1st lot Dec ’06 - Install last lot

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IR2 BPM Upgrade PlanIR2 BPM Upgrade Plan

Remove 15 mm button and leave 2.4 mm center pin as button. Attempt to remove buttons in situ without removing chambers if

possible. Buttons will be leak checked from the reverse side if space permits. If failure occurs during attempt (leak or failure to remove button).

Replace with copper blank. Replace with new helicoflex sealed BPM similar to the new LER arc

BPM.

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BPM Removal ToolBPM Removal Tool

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SummarySummary

HER arcs and LER/HER straights BPM’s do not require an upgrade at this time.

There is an upgrade plan for LER arcs and IR2. Need to determine if BPM’s can be pulled in-situ. If not a decision to

remove the chambers or leave the BPMs “as is” will have to be made. Will need full support from physicists for RF/HOM analysis because

the design & procurement cycle is long for new BPMs.