1. Radial Ion Pump, BPMs, & HOM Bellows Machine Advisory Committee Meeting December 14, 2004 Nadine Kurita Machine Advisory Committee Meeting December 14, 2004 Nadine Kurita

2. PEP-II Vacuum p2  Radial Ion Pump  Beam Position Monitors  HOM Bellows  Q4/Q5 Bellows + absorber  Straight HOM Bellows  Q2 HOM Bellows Outline

3. PEP-II Vacuum p3 Contributers/ Upgrade Staff  Physicists  Michael Sullivan  John Seeman  Stan Ecklund  Sasha Novokhatski  Stephen Weathersby  Cho K. Ng  Artem Kulikov  Uli Wienands  Designers  Ho Dong  Manual Trigos  Michael Kosovsky  Engineering  Nadine Kurita  Dan Wright

4. PEP-II Vacuum p4 B1 Radial Ion Pump  Pump modeled after PEP-I, SPEAR and the Damping Ring.  Detail design of cell arrays engineered by C. Perkins 1998.

5. PEP-II Vacuum p5 B1 Radial Ion Pump Prodec Anode cell structure Tantalum Cathode Plates Ceramic Standoff  2mm holes Baffles  Modified to Ta from Ti to increase noble gas pumping and eliminate the argon instability. Additional BPM set Reduced to 4 cell arrays from 6.  Shorten pump to add BPM set.

6. PEP-II Vacuum p6 B1 Radial Ion Pump Create two independent pumping cells  Pro: if a cell fails you still have another operational unit  Con: you are 2 times as likely to have a failure. Standard pump feedthrough  Current feedthrough rated fo 6 kV  Pump operates at 5.5 kV  Standard feedthrougs rated for 12 kV, 10A

7. PEP-II Vacuum p7 B1 Radial Ion Pump  Pump cell array is unchanged  Cell diameter optimized for pumping speed and operating pressure  .36 cm for a Penning cell in a 15 kilogauss field at 1 x 10 -9 Torr pressure.  Speed versus diameter curve is flat above .2 cm so the hole size is driven by manufacturability.  2:1 cell height to cell diameter ratio gives optimum surface coverage for sputtering on the anode.  .48 cm  Need to review depth

8. PEP-II Vacuum p8 Ion Pump  Holes & baffles unchanged  .094” x.245 deep  Baffles to prevent SR from striking anodes or cathodes.  No direct line of sight

9. PEP-II Vacuum p9 Ion Pump Milestones  Final Design Review 1/05  Order long lead items 1/05  Tantalum plates  Complete piece detail part drawings 3/05  Receive piece parts 5/05  Assemble, bake 7/05

10. PEP-II Vacuum p10 Beam Position Monitor (BPM)  Upgrade improvements  Added BPM set at each radial ion pump.  The new set is separated in z by ~f * 7.9 cm from the BPM’s in the B1 chamber, where f = 2.  7.9 cm corresponds to a quarter wavelength of 952 MHz, the BPM procesing frequency.  In the electronics they can then synthesize independent linear combinations of the signals which correspond to the two beams moving in opposite directions. ~ 2*7.9

11. PEP-II Vacuum p11 Q4R looking downbeam e- Q5L looking downbeam e- BPM’s in Replacement Chambers  HER Q4 & Q5 Chambers  Located at the outboard end of Q4 and outboard end of Q5.  Use spare PEP-II BPMs for Al chambers (LER arc style).

12. PEP-II Vacuum p12 Improvements HER Q4/Q5 BPM’s  Bellows allows the Q5 BPM to be rigidly supported (xx, y z). Q4 BPM is held in x, yy  Greater thermal stability  Lowered thermal gradients  Support BPM to Quad magnet  No calibration required – QMS/BBA  BPM’s are centered on the beam in the x-direction,  BPM center to BPM center x- spacing determined by (R. Johnson, S. Smith (2004).  Place BPM’s on flat surfaces.

13. PEP-II Vacuum p13 BPM’s (cont.)  Spares  HER Arc Style (CuNi Housing) – 3 units  LER Arc Style (Tin seal housing) – 44 units  Straight Style (SS Housing) – 2 units  Total quantity needed  Radial ion pump – 8  HER Q4/Q5 – 16  LER Q4/Q5 – 16  Could use LER Arc Style, but HER Arc style preferred  Total 44 BPM’s  Equals spare quantity of LER arc style  No loss of units, no additional sets if possible

14. PEP-II Vacuum p14 BPM History  PEP-II - purchased alumina borosilicate glass feedthroughs from Kaman Instrumentation.  ~2002 Meggit Safety Systems purchased Kaman Instrumentation.  2003 Meggit produced spare BPM's for SPEAR3  XPS analysis shows product to be incompatible with vacuum.  ~2002 Times Microwave starts up a new division with the Kaman engineers to produce borosilicate connectors and feedthroughs.  Times has no rights to our PEP-II or SPEAR3 design.  New process and ceramic to produce the seal. This technology is better for vacuum cleanliness, but we have no history on the integrity of the seal.  ~2004 Bejing receives BPM's from Times that leaked after welding.

15. PEP-II Vacuum p15 BPM Vendor Selection  Meggit  Pros: They have detailed drawings and procedures to fabricate our BPM's.  Cons: They are not as responsive as Kaman was.  Cons: They have not successfully built a clean vacuum component.  Times  Pros: They have the original engineers that helped develop the PEP-II BPMs.  Pros: They are responsive.  Cons: Unproven design and manufacturing of the seals. We would require R&D funds to validate their sealing technology and connector reliability.  Cons: It would be beneficial to develop another company that could produce BPM's for the lab in the future.  Cons: Long term viability of the RF instrumentation division.

16. PEP-II Vacuum p16 BPM Future Tasks  Clean the Meggit SPEAR3 BPMs with a non- corrosive solution, bake and RGA scan.  Re-develop with Times a comparable BPM's.  These BPM's should be electrically identical to the PEP-II BPM's and they must meet our technical specification.  Testing per the SLAC specification  Estimated lead time for fabrication is 10 weeks from Times. Potentially longer lead time for Meggit.

17. PEP-II Vacuum p17 Q4/Q5 Bellows & Absorber  Major Requirements  HER: 2.2A, 9Gev  Beam stay clear  12  + 0 mm in X  9  + 0 mm in Y  Luminosity Cone : 6.24   Synchrotron Radiation  No SR power strikes the bellows module  Mis-steer  RF fingers protected by chambers  ± 1 mrad in X – requirement  ± 2 mrad in Y – requirement  Forward > 5 mrad  Backward > 25 mrad  HOM power, Scattered SR, Ohmic  Engineering estimate: 1 KW/m

18. PEP-II Vacuum p18 Q4/Q5 Bellows Requirements (cont.)  Modular Design – 4.25”  Operating Temperatures  Tmax Finger < 100ºC  500 C @ 10 hrs w/ minimal stress relaxation  0ºC - 100ºC, Installed  200ºC Bake Out, Manufacturing  Chamber Operating Temperatures  Cold Day 0  C  ~  Tave = 45  C  Allows for misalignment and manufacturing tolerances of mating chambers.  Allows for thermal expansion of mating chambers.  Installation space for chambers.  Load bolts from bellows.  Space is tight – may need to remove corrector

19. PEP-II Vacuum p19 Q4/Q5 Bellows Layout Q4 side, 10” flange Q5 side 12” flange GlidCop Stub Inconel Spring Finger GlidCop RF Shield Finger Welded Bellows Cooling – not shown Absorbing Tile

20. PEP-II Vacuum p20 Q4/Q5 Blws Detail Design  HER Arc Bellows concept with absorber  Ensure failure does not result in the RF shield falling into beam tube  Shield fingers slide on outside of chamber stub  Keep high stress areas away from high heat areas  Keep steps to a minimum, reduce impedance  Plating to minimize wear, decrease cold welding, solid lubrication

21. PEP-II Vacuum p21 Q4/Q5 Blws Aperture  SR passes both directions  Stub can’t protect thin RF shield fingers  Backward side  Mask on chambers protect bellows from large misteers  Forward side  Chamber walls protect bellows from 5 mrad misteer e- Forward e- Backward.080 step at stub  BSC grows in Q5  No taper – step at stub only e+ Backward

22. PEP-II Vacuum p22 Q4/Q5 Blws - Absorber  Three options for absorber placement.  #1 - Directly above RF shield fingers  #2 - Above the Spring Fingers  #3 - In the bellows cavity space  Tile is located in the HOM cavity  Creates another vacuum joint   Makes GlidCop stub a mechanical braze & not a vacuum braze.  Latest design uses option #3.  All options probably absorb the trap mode between the RF shield fingers and the welded bellows  Sasha/Stephen have a model of option 1. Option 3 next week. Option 1 Option 3

23. PEP-II Vacuum p23 Q4/Q5 Blws - Absorber Analysis  Tile  Actual size and quantity TBD. Engineering evaluation assumes optimal tile volume.  Size.4 x.47 x.5  14 tiles in module  Ceralloy 13740  K = 30 W/m-C  Flexural strength 43.5 ksi  HOM power  2 KW assumed  Ansys Results  Tcool = 51  C  Tmax tile = 240  C   tile z25 ksi

24. PEP-II Vacuum p24 HOM Absorbing Bellows

25. PEP-II Vacuum p25 HOM Absorbing Bellows  New bellows designs that also function as beamline HOM absorbers.  LER arc bellows  Straight bellows  Q2 bellows  New bellows designs that have absorbers that protect themselves from modes that leak behind their RF shields.  Vertex bellows  Q4/Q5 bellows

26. PEP-II Vacuum p26 Straight HOM Blws -Design Details GlidCop Stub Inconel Spring Finger GlidCop RF Shield Finger Welded Bellows Absorbing Tile 2.75” long by.24” wide HOM Trapping Slots Modes in the chamber propagate through the slots & are absorbed by the AlNiSiC. Bellows Cavity Modes that leak past the RF shield finger and are trapped in this area still see the absorber

27. PEP-II Vacuum p27 Straight Section HOM Bellows  Prototype of the HOM absorbing bellows  Simple round geometry  Locate near isolation valves to tests its impact on HOMs in neighboring components.  Conceptual design near completion  HOM calculations are being done to optimize tile size and slot dimensions.  Initial HOM analysis shows that the concept works.  Reduces monopole absorption while optimizing dipole and quadrupole field absorption.

28. PEP-II Vacuum p28 Near IR Layout

29. PEP-II Vacuum p29 Q1/Q2 HOM Bellows  FY2003 added 4 layers of tiles per module.  Absorbing ~10 KW presently  Predict ~ 50 KW in 2007  Numerous iterations on HOM absorbers have been analyzed by S. Weathersby and A. Novokhatski (38 runs).  Goal: Create a HOM absorber that doesn’t generate ~50% of its absorption power.  Reduce monopole without significantly reducing dipole and quadrupole modes  Most effective design requires at minimum 4” slots as in the Straight HOM Bellows.  The optimized design for various modes must be chosen by February 2005.  A few more design/analytical iterations will be performed  Reduce power absorption, but still reduce HOM power at the vertex ends, vertex bellows and radial ion pump.  Vertex bellows will have HOM tiles  Gold plating will be extended on the vertex ends.

30. PEP-II Vacuum p30 Q1/Q2 Blws - HOM Analysis  4” long tile sets  Suppresses the monopole mode without reducing the dipole and quadrupole mode  Sasha calculated the set back of the tiles  Focusing on 2” long tile sets  Reasonable length for the 5” bellows module

31. PEP-II Vacuum p31 Q1/Q2 Blws - Design Status  New concept developed  based on best information available.  Maximum Tile/slot length  ~2.4”  Absorbing tiles is open to the convolutions  No additional tile set needed in bellows cavity.  HER Arc Style Bellows  Spring  Stub  RF shield  Possibly reduce further the travel and offset requirements to increase length.

32. PEP-II Vacuum p32 Q1/Q2 Blws - Major Milestones  Finalize Physics/HOM Reqs Feb ’05  Conceptual Design ReviewMar ‘05  Final Design ReviewApr ‘05  Long Lead Procurements Apr ‘05  Detail Drawings CompleteJun ‘05  Receive PartsAug ‘05  Final AssemblySep ‘05  Ready for installationSep ‘05