Presentation is loading. Please wait.

Presentation is loading. Please wait.

26-October-2006 PEP-II MAC Session HOM measurement and analysis S. Weathersby, A. Novokhatski HOMs in LER region 4: overview, history Collimator wake fields.

Published byDominick Patterson Modified over 8 years ago

Similar presentations

Presentation on theme: "26-October-2006 PEP-II MAC Session HOM measurement and analysis S. Weathersby, A. Novokhatski HOMs in LER region 4: overview, history Collimator wake fields."— Presentation transcript:

1 26-October-2006 PEP-II MAC Session HOM measurement and analysis S. Weathersby, A. Novokhatski HOMs in LER region 4: overview, history Collimator wake fields Design of HOM selective absorber Experimental results LER abort spoiler investigations IP Q2 bellows

2 26-October-2006 PEP-II MAC Session Region 4 overview and history LER region 4 straight to arc transition temperatures unusually high: bellows, valves, pumps Burned antechamber TSP feedthru indicated HOMs coupling into accelerator components Temperature response to beam position at upstream collimator (10-15 meters away) Installed water cooled absorber in TSP pump chamber

3 26-October-2006 PEP-II MAC Session RF cavities 100 m TFB & LFB kickers 50 m Collimator 15 m HOMs in region 4

4 26-October-2006 PEP-II MAC Session Hot spots and diagnostics

5 26-October-2006 PEP-II MAC Session Antechamber absorber

6 26-October-2006 PEP-II MAC Session Recent developments Collimator wake field studies indicate presence of traveling waves: predominately dipole and quadrupole Design of selective HOM absorber: Intercept and dissipate harmful modes. Minimize beam impedance. Selective HOM absorber built and installed. Experimental data is encouraging

7 26-October-2006 PEP-II MAC Session downstream upstream Downstream electric field snapshots after bunch has passed 1.3 cm, 14 nC Gaussian bunch length ~0.6 m height ~ 3 cm Collimator wake fields downstream MAFIA Time domain

8 26-October-2006 PEP-II MAC Session downstream upstream Power propagation follows bunch Beam arrival

9 26-October-2006 PEP-II MAC Session How do we remove HOMs? The selective HOM absorber (trap) Devise a means to intercept traveling dipole/quadrupole HOMs before arc transition. Avoid disruption to beam image currents (monopole) Safely dissipate absorbed EM energy Ceramic tiles Coupling slots

10 26-October-2006 PEP-II MAC Session p1p2 FT Normalize to 1in Dipole mode example cuttoff Scattering parameters s 11, s 21 Port signals Analysis 1out/1in=s11 2out/1in=s21

11 26-October-2006 PEP-II MAC Session Optimal design Slot length: 70 mm Slot width: 6 mm Absorber thickness: 16.7 mm Slot length affects degree of coupling Slot width broadens spectra Absorber thickness lowers peak frequencies

12 26-October-2006 PEP-II MAC Session Experimental results Mechanical design and installation Experimental data Ceramic absorbing tiles Coupling slots Bellows cavity coupled to absorber Water cooling

13 26-October-2006 PEP-II MAC Session Tiles braised to water cooled copper support columns Ready for install Production

14 26-October-2006 PEP-II MAC Session Installation May 17, 2006

15 26-October-2006 PEP-II MAC Session Selective absorber installed 15 m More current, half the HOM heating

16 26-October-2006 PEP-II MAC Session 20 m Other bellows A

17 26-October-2006 PEP-II MAC Session Valve temperatures 14 m

18 26-October-2006 PEP-II MAC Session 20 m A At burned antechamber site

19 26-October-2006 PEP-II MAC Session Power at antechamber absorber

20 26-October-2006 PEP-II MAC Session Region 4 HOM Summary HOMs from collimators propagate large distances and infiltrate beam line structures with harmful RF energy Dipole and quadrupole modes predominate Selective absorber designed to specifically remove dipole and quadrupole HOM power from the beam chamber while presenting minimal disruption to beam image currents Selective absorber built and installed. Reduction in downstream temperature profiles

21 26-October-2006 PEP-II MAC Session LER abort spoiler investigations Diffuse aborted beam to protect abort window Large power measured during x4 bucket pattern at 500 mA (stored beam) Recent inspection revealed significant HOM damage

22 26-October-2006 PEP-II MAC Session Melted Ti

23 26-October-2006 PEP-II MAC Session Spoiler “trapped” mode 0.539 GHz Q factor 1097  r =30, loss tangent 0.11,  r =1 absorbs E fields Copper chamber and Ti spoiler 2mm wide spoiler 476 MHz/4*5=.595 GHz -> close to by4 Electric field 464 304

24 26-October-2006 PEP-II MAC Session Magnetic field near base of spoiler and tiles Magnetic field Vs/M 2 1.4e-7 6.7e-7

25 26-October-2006 PEP-II MAC Session Surface currents

26 26-October-2006 PEP-II MAC Session Power loss density W/M 2 High power loss density on the edge

27 26-October-2006 PEP-II MAC Session Power loss density VA/M 2 Spoiler edge effect Magnetic field

28 26-October-2006 PEP-II MAC Session Shorter spoiler: 5 cm,. 0.62 GHz More field near absorber. Q lower by factor of 2 Shorter spoiler 7cm -> 5 cm Electric field

29 26-October-2006 PEP-II MAC Session LER spoiler Summary Trapped mode has observed power loss profile 50 MHz from by 4 frequency. 1 cm Mainly magnetic field at absorber location (lossy Ferrite?) Current density high on outer edges. Change profile. Length effects: 7 cm=.54 GHz, 5 cm=.62 GHz. Factor of 2 lower Q Increasing resistance ~factor of 2 Q decrease. (A. Kulikov) Increasing conductance raises Q dangerously. Change length to avert resonance Stay away from by4 Graphite spoiler

30 26-October-2006 PEP-II MAC Session Existing Q2 bellows absorption

31 26-October-2006 PEP-II MAC Session New proposal

Download ppt "26-October-2006 PEP-II MAC Session HOM measurement and analysis S. Weathersby, A. Novokhatski HOMs in LER region 4: overview, history Collimator wake fields."

Similar presentations

Introduction to RF for Accelerators

Introduction to RF for Accelerators
S. N. HOM Impedance in Vacuum … 1 of 40 Sasha Novokhatski SLAC, Stanford University Machine-Detector Interface Joint Session April 22, 2005 HOM Impedance.

S. N. HOM Impedance in Vacuum … 1 of 40 Sasha Novokhatski SLAC, Stanford University Machine-Detector Interface Joint Session April 22, 2005 HOM Impedance.
Uniform plane wave.

Uniform plane wave.
1 BROOKHAVEN SCIENCE ASSOCIATES Stephen Kramer, VUV Ring Manager 1992-2002 CSR Emission Studies in VUV/IR Ring NSLS.

1 BROOKHAVEN SCIENCE ASSOCIATES Stephen Kramer, VUV Ring Manager CSR Emission Studies in VUV/IR Ring NSLS.
2006/9/25-26 ILCDR06, Cornell University 1 DESIGN STUDY OF A MOVABLE COLLIMATOR WITH LOW BEAM IMPEDANCE Yusuke Suetsugu*, Kyo Shibata KEKB Vac. Group Introduction.

2006/9/25-26 ILCDR06, Cornell University 1 DESIGN STUDY OF A MOVABLE COLLIMATOR WITH LOW BEAM IMPEDANCE Yusuke Suetsugu*, Kyo Shibata KEKB Vac. Group Introduction.
Upgrade Plan of KEKB Vacuum system 2008.03.19Pre-kickoff KEK1 Y. Suetsugu KEKB Vacuum Group Contents Challenges for vacuum system Designs for.

Upgrade Plan of KEKB Vacuum system Pre-kickoff KEK1 Y. Suetsugu KEKB Vacuum Group Contents Challenges for vacuum system Designs for.
Study of a Clearing Electrode at KEKB - First beam test - Y. Suetsugu, H. Fukuma (KEK), M. Pivi, W. Lanfa (SLAC) 2008/3/3-61TLC08 Sendai.

Study of a Clearing Electrode at KEKB - First beam test - Y. Suetsugu, H. Fukuma (KEK), M. Pivi, W. Lanfa (SLAC) 2008/3/3-61TLC08 Sendai.
2007.07.311 R&D Plan on Clearing Electrode using the KEKB LER Y. Suetsugu and H. Fukuma, KEKB M. Pivi and L. Wang, SLAC 2007. 07. 31 at KEK.

R&D Plan on Clearing Electrode using the KEKB LER Y. Suetsugu and H. Fukuma, KEKB M. Pivi and L. Wang, SLAC at KEK.
S. N. “ Cavities for Super B-Factory” 1 of 38 Sasha Novokhatski SLAC, Stanford University Accelerator Session April 20, 2005 Low R/Q Cavities for Super.

S. N. “ Cavities for Super B-Factory” 1 of 38 Sasha Novokhatski SLAC, Stanford University Accelerator Session April 20, 2005 Low R/Q Cavities for Super.
8 th ESLS RF Meeting 29 th – 30 th Sep. 2004 Daresbury Lab 500 MHz ELETTRA Input Power Coupler B. Baricevic, A. Fabris, C. Pasotti.

8 th ESLS RF Meeting 29 th – 30 th Sep Daresbury Lab 500 MHz ELETTRA Input Power Coupler B. Baricevic, A. Fabris, C. Pasotti.
PEP-II B Factory Machine Status and Upgrades John T. Seeman for the PEP-II Staff SLAC DOE Site Review April 9, 2003.

PEP-II B Factory Machine Status and Upgrades John T. Seeman for the PEP-II Staff SLAC DOE Site Review April 9, 2003.
Super-B Factory Workshop January 19-22, 2004 Beam pipes M. Sullivan 1 Detector Beam Pipe Diameter Discussion M. Sullivan Super-B Factory Workshop Hawaii.

Super-B Factory Workshop January 19-22, 2004 Beam pipes M. Sullivan 1 Detector Beam Pipe Diameter Discussion M. Sullivan Super-B Factory Workshop Hawaii.
June 2-4, 2004 DOE HEP Program Review 1 M. Sullivan for the PEP-II Team DOE High Energy Physics Program Review June 2-4, 2004 PEP-II Status and Plans.

June 2-4, 2004 DOE HEP Program Review 1 M. Sullivan for the PEP-II Team DOE High Energy Physics Program Review June 2-4, 2004 PEP-II Status and Plans.
01/07/2005 SN 1 of 16 Esti mation of HOM Power in the Interaction Region of ILC Sasha Novokhatski Session “Beam RF Effects” ILC MDI Workshop SLAC January.

01/07/2005 SN 1 of 16 Esti mation of HOM Power in the Interaction Region of ILC Sasha Novokhatski Session “Beam RF Effects” ILC MDI Workshop SLAC January.
12/13/2004 SN PEP-II MAC REVIEW 1 of 49 RECENT HOM CALCULATIONS HOM Dampers: Last Measurements and New Computer Designs Sasha Novokhatski PEP-II MAC Review.

12/13/2004 SN PEP-II MAC REVIEW 1 of 49 RECENT HOM CALCULATIONS HOM Dampers: Last Measurements and New Computer Designs Sasha Novokhatski PEP-II MAC Review.
Design of Standing-Wave Accelerator Structure

Design of Standing-Wave Accelerator Structure
1 IR NEG heating M. Sullivan MAC Review Dec. 13-15, 2004 M. Sullivan Machine Advisory Committee Review December 13-15, 2004 IR NEG Heating and Upgrade.

1 IR NEG heating M. Sullivan MAC Review Dec , 2004 M. Sullivan Machine Advisory Committee Review December 13-15, 2004 IR NEG Heating and Upgrade.
RF Cavity of CIS Xiaoying Pang Mar. 12 th, 2007 IUCF.

RF Cavity of CIS Xiaoying Pang Mar. 12 th, 2007 IUCF.
Vacuum Pressures at IR Contents Y.Suetsugu KEKB Vac. Group 1.Outline of Vacuum System at IR 2.Behavior of Pressures 3.Remedies for Heating of Vacuum Components.

Vacuum Pressures at IR Contents Y.Suetsugu KEKB Vac. Group 1.Outline of Vacuum System at IR 2.Behavior of Pressures 3.Remedies for Heating of Vacuum Components.
Future Very High Luminosity Options for PEP-II John T. Seeman For the PEP-II Team e+e- Factories Workshop October 13-16, 2003.

Future Very High Luminosity Options for PEP-II John T. Seeman For the PEP-II Team e+e- Factories Workshop October 13-16, 2003.

Similar presentations

Ads by Google