HOM working group

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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 βg

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 βg

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

-- MarcelSchuh - 13 June 2009

Topic attachments
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PDFpdf FQspread.pdf r1 manage 86.3 K 2009-06-26 - 08:46 UnknownUser  
PDFpdf FR5REP053.pdf r1 manage 862.7 K 2009-05-28 - 16:25 UnknownUser  
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