HOM working group

How to edit this page: register here and send a mail with your TWIKI name to frank.gerigk@cernNOSPAMPLEASE.ch asking for access to the "SPL HOM pages".

collection of data relevant for HOM studies in the SPL.

See also the recent SPL HOM workshop at CERN (25/26 June 2009).

1. Beam parameters
2. HOM parameters
3. Publications

Beam parameters (see also: https://twiki.cern.ch/twiki/bin/view/SPL/SPLparameterList)

parameter	value	Comment	Time stamp
current	40 - 400 mA		28 May 2009
bunch frequency	352.2 MHz		28 May 2009
RF frequency	704.4 MHz		28 May 2009
cavity gradient	19/25 MV/m	beta = 0.65/1.0	28 May 2009
synchronous phase	-15 deg		28 May 2009
cells per cavity	5/5	beta = 0.65/1.0	28 May 2009
cavities per focusing period	3/8	beta = 0.65/1.0	28 May 2009
repetition rate	50 Hz		28 May 2009
max. beam energy	5 GeV		28 May 2009
simulation input noise
σx	0.3 mm	Linac4 simulation	23 June 2009
σx'	0.3 mrad	Linac4 simulation	23 June 2009
σW	78.00 keV	Linac4 simulation	23 June 2009
σPhase	0.4 deg	Linac4 simulation	23 June 2009

HOM parameters

Monopole modes in SPL cavities

no	mode	frequency [MHz]	(R/Q)† [Ω]	Comment	Time stamp
low beta section: βg=0.65, 5-cell cavity
4	TM010,4/5π	703.7	1	HFSS	28 May 2009
5	TM010,π	704.4	318	HFSS, accelerating mode	28 May 2009
12	TM011,3/5π	1765	3	HFSS	28 May 2009
13	TM011,4/5π	1774	4	HFSS	28 May 2009
-	TM01	2550		cutt off freq.	24 June 2009
high beta section: βg=1.0, 5-cell cavity
3	TM010,3/5π	698.9	35	HFSS	23 June 2009
5	TM010,π	704.4	560	HFSS, accelerating mode	21 January 2010
9	TM011,4/5π	1322	37	HFSS	23 June 2009
10	TM011,π	1331	137	HFSS	28 May 2009
27	TM021	2090	25	HFSS	28 May 2009
28	TM021	2107	12	HFSS	23 June 2009
36	TM022	2456	14	HFSS	23 June 2009
-	TM01	1639		cutt off freq.	24 June 2009

† linac definition, caclulated at β_g

Dipole modes in SPL cavities

no	mode	frequency [MHz]	(R/Q)† [Ω]	Comment	Time stamp
low beta section: βg=0.65, 5-cell cavity
1	TM110,1/5π	1015	2	HFSS	23 June 2009
2	TM110,2/5π	1020	19	HFSS	23 June 2009
3	TM110,3/5π	1027	28	HFSS	23 June 2009
4	TM110,4/5π	1033	6	HFSS	23 June 2009
6	TE111,1/5π	1270	13	HFSS	23 June 2009
7	TE111,2/5π	1299	4	HFSS	23 June 2009
17	TE	1760	2	HFSS	23 June 2009
18	TE	1788	3	HFSS	23 June 2009
high beta section: βg=1.0, 5-cell cavity
3	TE111,3/5π	915.1	18	HFSS	23 June 2009
4	TE111,4/5π	939.8	33	HFSS	23 June 2009
5	TE111,π	966.4	14	HFSS	23 June 2009
7	TM110	1003	8	HFSS	23 June 2009
8	TM110	1014	19	HFSS	23 June 2009
9	TM110	1020	6	HFSS	23 June 2009
16	TE	1393	11	HFSS	23 June 2009
18	TE	1409	12	HFSS	23 June 2009
27	TE	1607	3	HFSS	23 June 2009

† linac definition, caclulated at β_g

HOMs in other cavities

mode	beta	frequency [MHz]	(R/Q)† [Ω]	Comment	Time stamp
TESLA/XFEL/ILC
Monopole	1.0	2450/2457	155/130	-	28 May 2009
Dipole	1.0	1739/1736	120/59	-	28 May 2009
Quadrupole	1.0	3253	3	-	28 May 2009
SNS
Monopole	0.61	2206/804	4/131	-	28 May 2009
Dipole	0.61	1144	45	-	28 May 2009
Quadrupole	0.61	1561	3	-	28 May 2009
Monopole	0.81	1755/804	38/145	-	28 May 2009
Dipole	0.81	1143	87	-	28 May 2009
Quadrupole	0.81	1566	4	-	28 May 2009

Other input parameters for HOM BBU simulations

parameter	value	Comment	Time stamp
HOM frequency scatter, TESLA	1 - 10 MHz	measured for 1.3 GHz Tesla type cavities, source: J. Sekutowicz, DESY	28 May 2009
HOM frequency scatter FLASH	~3 MHz	measured in all FLASH cavities for one dipole HOM at around 1.7 GHz, polarisations of the same mode usually within 0.5 MHz, source: S. Nagaitsev	28 May 2009
HOM frequency scatter, LEP	not measured	352.2 MHz, source: J. Tückmantel, CERN	28 May 2009
HOM frequency scatter, LHC	?	single cell, 400 MHz
HOM frequency scatter, SPL	1 MHz	extrapolation of above results	23 June 2009
HOM frequency scatter CEBAF	1.5 - 15 MHz	modes between 2.6 and 3 GHz (see plot by R. Rimmer)	25 June 2009
HOM frequency scatter CEBAF	0.3 - 30 MHz	modes between 1.7 and 2.2 GHz (see plot by R. Rimmer)	25 June 2009
HOM (R/Q)xQex uncertainty	10 - 100	observed at JLAB and TTF/FLASH, simulated at Cornell	23 June 2009
safety factor on current or (R/Q)Q	10	see above	23 June 2009
minimum distance of HOMs to multiples of bunch rep. rate	?	?
bunch charge jitter	assume: 3%	see presentation by S.H. Kim at SPL HOM workshop	29 Jun 2009

Other information

• if the SPL is used for electron acceleration with a re-circulator, then we may get rep rates in the MHz range, which leads to a very dense machine line spacing (S. Nagaitsev),

relevant documents

• Notes
  • Code Benchmarking of Higher Order Modes Simulation Codes, M. Schuh, J. Tückmantel, J.-L. Biarrotte, D. Kaltchev, CERN-sLHC-Project-Note-0010, 2010
  • Hom dampers or not in Superconducting RF Proton Linacs, J. Tückmantel, CERN-BE-Note 2009-009
  • HOM findings and HOM induced power in the superconducting linac of the intense pulsed proton accelerator, S. Kim, et al., SNS-AP Technical Note Vol. 10, 2001.
  • Monopole, Dipole and Quadrupole passbands of the TESLA 9-cell cavity, R. Wanzenberg, DESY-TESLA-2001-33.

• Conference publications
  • Higher Order Mode Analysis of the SPL Cavities, M. Schuh, F. Gerigk, J. Tückmantel, C.P. Welsch, IPAC 2010
  • Higher Order Mode Beam Breakup Limits in the Superconducting Cavities of the SPL, M. Schuh, F. Gerigk, J. Tückmantel, C.P. Welsch, SRF 2009
  • Higher order modes in the SC cavities of the SPL, F. Gerigk, M. Schuh, J. Tückmantel, C.P. Welsch, PAC 2009
  • SNS HOM damping requirements via bunch tracking, R. Sundelin et al, PAC 2001

• Journal papers
  • Beam simulations with initial bunch noise in superconducting rf proton linacs, J. Tückmantel, PRSTAB 13, 011001 (2010)
  • High precision superconducting cavity diagnostics with higher order mode measurements, S. Molloy et al., PRSTAB 9, 112802 (2006).
  • Cumulative beam break-up study of the spallation neutron source superconducting linac, D. Jeon et al, Nucl. Instr. Meth. A 495 (2002) 85-94
  • Higher order mode (HOM) power in elliptical superconducting cavities for intense pulsed proton accelerators, S.H. Kim et al, Nucl. Instr. Meth. A 492 (2002) 1-10

• Talks
  • New SRF developments for the Cornell ERL, M. Liepe, TTC meeting, 16-19 June Orsay
  • Status of SPL HOM studies at TRIUMF, R. Baartman, 2nd SPL collaboration meeting, Triumf, 8-9 May 2009.
  • HOM damping ideas for the next generation of the BNL/AES 704 MHz beta=1 cavity, I. Ben Zvi, 2nd SPL collaboration meeting, Triumf, 8-9 May 2009.
  • Do we need HOM dampers on SC cavities in p-linacs?, J. Tuckmantel, 1st SPL collaboration meeting, CERN, December 11-12 2008.
  • HOM studies for TESLA, H-W. Glock, 1st SPL collaboration meeting, CERN, December 11-12 2008.
  • HOM damping on SC cavities, J. Tuckmantel, 1st SPL collaboration meeting*, CERN, December 11-12 2008.
  • Power dissipation in HOMs (SPL), M. Schuh, SPL study group meeting, November 19 2008.
  • HOM damping (ILC type cavities), J. Sekutowicz, ILC workshop, KEK, November 13-15 2004.

• Plots
  • Frequency and loaded Q spread for CEBAF cavities, R. Rimmer, June 26th 2009.

-- MarcelSchuh - 13 June 2009