Post on 05-Feb-2016
description
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
Vacuum System p.2
OutlineOutline
BPM Upgrade project overview
2005 upgrade/testing
LER Arc BPM’s
IR2 BPM’s
Summary
Vacuum System p.3
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
Vacuum System p.4
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
Vacuum System p.5
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
Vacuum System p.6
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.
Vacuum System p.7
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
Vacuum System p.8
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
Vacuum System p.9
Alumina Feedthru Layout DrawingAlumina Feedthru Layout Drawing
Vacuum System p.10
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
Vacuum System p.11
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
Vacuum System p.12
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
Vacuum System p.13
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.
Vacuum System p.14
BPM Removal ToolBPM Removal Tool
Vacuum System p.15
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.