collective effects and beam measurements in particle accelerators

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F. Ruggiero Univ. “La Sapienza”, Rome, 20–24 March 2006 CERN Collective Effects and Beam Collective Effects and Beam Measurements in Particle Measurements in Particle Accelerators Accelerators beam diagnostics and fundamental beam diagnostics and fundamental limitations to the performance of high- limitations to the performance of high- intensity accelerators intensity accelerators See also slides on Measurements, ideas, curiosities http://ab-abp-rlc.web.cern.ch/ab-abp-rlc/

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Collective Effects and Beam Measurements in Particle Accelerators. beam diagnostics and fundamental limitations to the performance of high-intensity accelerators. http://ab-abp-rlc.web.cern.ch/ab-abp-rlc/. See also slides on Measurements, ideas, curiosities. Wakefield for a pill-box cavity. - PowerPoint PPT Presentation

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Page 1: Collective Effects and Beam Measurements in Particle Accelerators

Name Event DateName Event Date11

F. Ruggiero Univ. “La Sapienza”, Rome, 20–24 March 2006CERN

Collective Effects and Beam Collective Effects and Beam Measurements in Particle Measurements in Particle

AcceleratorsAcceleratorsbeam diagnostics and fundamental beam diagnostics and fundamental

limitations to the performance of high-limitations to the performance of high-intensity acceleratorsintensity accelerators

See also slides on Measurements, ideas, curiosities

http://ab-abp-rlc.web.cern.ch/ab-abp-rlc/

Page 2: Collective Effects and Beam Measurements in Particle Accelerators

Name Event DateName Event Date22

F. Ruggiero Collective Effects and Beam MeasurementsCERN

Wakefield for a pill-box Wakefield for a pill-box cavitycavity• Animation showing a bunch of charged Animation showing a bunch of charged

particles moving on the cavity axis and the particles moving on the cavity axis and the corresponding electric field lines computed corresponding electric field lines computed by the program ABCIby the program ABCI

• Courtesy Andreas Wagner Courtesy Andreas Wagner http://awagner.home.cern.ch/awagner/http://awagner.home.cern.ch/awagner/

Page 3: Collective Effects and Beam Measurements in Particle Accelerators

Name Event DateName Event Date33

F. Ruggiero Collective Effects and Beam MeasurementsCERN

TRISIM3D simulation of a LEP TRISIM3D simulation of a LEP bunchbunch

EE = 22 GeV, = 22 GeV, QQss = 0.092, = 0.092, II = 0.3 = 0.3 mA mA • 3-dimensional computer simulation of single 3-dimensional computer simulation of single

bunch collective effects in particle acceleratorsbunch collective effects in particle accelerators• top and side view of the particle distribution turn top and side view of the particle distribution turn

by turn, over 60 turnsby turn, over 60 turns • Courtesy Andreas Wagner Courtesy Andreas Wagner

http://awagner.home.cern.ch/awagner/http://awagner.home.cern.ch/awagner/

Page 4: Collective Effects and Beam Measurements in Particle Accelerators

Name Event DateName Event Date44

F. Ruggiero Collective Effects and Beam MeasurementsCERN

CERN Linac4CERN Linac4layout and parameterslayout and parameters

DTL CCDTL SCL

3MeV 40MeV 90MeV 160MeV

Drift TubeLinac

352 MHz13.4 m3 tanks5 klystrons4 MW

Side Coupled Linac

704 MHz28 m20 tanks4 klystrons12 MW

Cell-Coupled Drift TubeLinac352 MHz25.3 m24 tanks8 klystrons6.5 MW

Duty cycle:0.1% phase 1 (Linac4)3-4% phase 2 (SPL)(RF design: 15%)

4 different structures, (RFQ, DTL, CCDTL, SCL) 2 frequencies

Total Linac4: 80 m, 18 klystrons

current: 40 mA (avg. in pulse), 65 mA (bunch)

CHOPPERRFQ

Chopper

352 MHz3.6 m

Radio FrequencyQuadrupole

352 MHz6 m1 Klystron1 MW

H-

3MeV95keV

Courtesy A. LombardiCourtesy A. Lombardi

Page 5: Collective Effects and Beam Measurements in Particle Accelerators

Name Event DateName Event Date55

F. Ruggiero Collective Effects and Beam MeasurementsCERN

Instabilities in a LinacInstabilities in a Linac

Courtesy A. LombardiCourtesy A. Lombardi

=Longitudinal to transverse phase advance

Tra

nsv

ers

e t

une d

epre

ssio

n

Page 6: Collective Effects and Beam Measurements in Particle Accelerators

Name Event DateName Event Date66

F. Ruggiero Collective Effects and Beam MeasurementsCERN

Intra-Beam Scattering Intra-Beam Scattering (simplified formulae by K. Bane, EPAC 2002)(simplified formulae by K. Bane, EPAC 2002)

• For the LHC, the average For the LHC, the average dispersion invariant is dispersion invariant is <<HHxx>~0.03 m, >~0.03 m, avav~100 m, ~100 m, and the Coulomb logarithm and the Coulomb logarithm (log)~24(log)~24

• Note that the transverse IBS Note that the transverse IBS growth rate is about growth rate is about proportional to the particle proportional to the particle density in the 6D phase density in the 6D phase space space NNbb/(/(zz

x

avb

2p

3δz

2/33IBSz

1

)log(

8 H

cNr

x2δ

IBSz

IBSx H

IBS growth times for IBS growth times for long super-bunches in long super-bunches in the LHC as a function of the LHC as a function of the rms momentum the rms momentum spread spread