bnl r&d erl and coherent electron cooling test at rhic
DESCRIPTION
BNL R&D ERL and Coherent Electron Cooling test at RHIC. Outline Goals of R&D ERL at BNL ERL general layout and main components Coherent electron cooling test at RHIC Plans & Conclusions. e-cooling (RHIC II). PHENIX. Main ERL (3.9 GeV per pass). STAR. e + storage ring - PowerPoint PPT PresentationTRANSCRIPT
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
BNL R&D ERL and Coherent Electron Cooling test at RHIC
OutlineOutline• Goals of R&D ERL at BNL• ERL general layout and main components• Coherent electron cooling test at RHIC• Plans & Conclusions
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
PHENIX
STAR
e-cooling (RHIC II)
Four e-beam passes
e+ storage ring 5 GeV - 1/4 RHIC circumference
Main ERL (3.9 GeV per pass)
IntroductionIntroduction
R&D ERL will serve as a test-bed for future RHIC projects:• ERL-based electron cooling (conventional or coherent),• 10-to-20 GeV ERL for lepton-ion collider eRHIC.
It will also address general issues expanding capabilities of ERLs:
• novel SRF injector,• high current and high brightness beam ERL operation,• flexible lattice to enable covering a vast operational parameter space.
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
Goals for ERL R&D at BNL
• Test the key components of the High Current Energy Recovery Linac based solely on SRF technology– 703.75 MHz SRF gun test with 500 mA – high current 5-cell SRF linac test with HOM absorbers
• Single turn - 500 mA – test the beam current stability criteria for CW beam currents – Demonstrate beam quality close to that required for high energy
electron cooling• Test the attainable ranges of electron beam parameters in SRF ERL
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
50 kW 703.75 MHzsystem
Control room
Cryo-module
SRF cavity
1 MW 703.75 MHzKlystron
e- 2.5MeV
Laser
SC RF Gun e- 2.5 MeV
Beam dump
Cryo-module
e- 15-20 MeV
Schematic Layout of the ERL
Merger system
Return loop
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
Half cell SRF Gun
SuperFish File Gun 5cm Iris NO transition Section F = 703.68713 MHz
C:\DOCUMENTS AND SETTINGS\KAYRAN\MY DOCUMENTS\ERL\SCGUN_DESIGN\FROM_RAM\RGUN51.AM 4-25-2005 10:50:06
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Electromagnetic field data from file GUN4MM.AMProblem title line 1: SuperFish File Gun 5cm Iris
GUN4MM01.TBL 8-31-2005 15:13:54
Z (cm)
0
.5
1
1.5
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2.5
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0 2 4 6 8 10 12 14 16 18 20 22 24Er
A. M. M. Todd et al., “State-of-the-Art Electron Guns and Injector Designs for Energy Recovery Linacs”,PAC2005
SC RF Gun: shape and axial electric field profile (SUPERFISH result)
fRF= 703.75 MHzEnergy=2.5-3 MeV
Average Current: 0.5 ATwo fundamental power couplers: 0.5 MW each
1.9
1.95
2
2.05
2.1
0 10 20 30 40 50 60
Launch Phase, deg
Ene
rgy,
MeV
Electron beam energy gain at the exit of the gun versus initial phase
Electromagnetic field data from file RGUN6.AMProblem title line 1: SuperFish File Gun 6cm Iris NO transition Section
RGUN601.TBL 4-25-2005 11:49:52
Z (cm)
0
.5
1
1.5
2
2.5
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0 2 4 6 8 10 12 14 16 18 20 22 24
Ez
Er
SC RF Gun: axial electric field profile for different cathode insertion depth (SUPERFISH result)
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
BNL R&D ERL SRF Injector layoutBNL R&D ERL SRF Injector layout
SRF GunSRF Linac
Z-merger Dipoles
Solenoids
ERL Loop
Dipole
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
Evolution of normalized beam emittances in the BNL R&D ERL injector
15º
-15º-30º
99.5 cm
70 cm
70 cm
30º
SC RF Gun5 cell SC RF cavity
0 2 4 6 8 100
5
10
15
Length, m
Rm
s N
orm
aliz
ed E
mitt
ance
s, m
m m
rad
12.075
0
xn0
xn1
xn2
8.3120 s0 s0 s1 s1 s2 s2 s3 s3
0 2 4 6 8 100
20
40
60
80
100
120
Length, m R
ms
Nor
mal
ized
Em
ittan
ces,
mm
mra
d
101.925
0
yn0
yn1
yn2
8.3120 s0 s0 s1 s1 s2 s2 s3 s3
Blue 5 nC Red 1.4 nC Green 0.7 nC
4.8/5.3 um 2.2/2.3 um 1.4/1.4um
Horizontal Vertical
BNL ERL Injector: beam dynamics simulation results
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
ERL: loop layoutERL: loop layout
2-3 MeV
2-3 MeV
20 MeV
20 MeV
20 MeV
2-3 MeV
SC RF GunSC 5 Cell cavity
Beam dump
Modes of operation Critical parameters
High energy acceptance Low dispersion, large aperture
Beam break up instability study Adjustable transverse phase advance
Longitudinal motion study Adjustable longitudinal dispersion
Two pass acceleration Changeable path length
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
ERL loop lattice is very flexibleERL loop lattice is very flexibleLattice and D functions of the ERL for the different cases longitudinal dispersions
(Ds=M56):
Positive longitudinal dispersion
Negative longitudinal dispersion
Zero longitudinal dispersion
No dispersion
Dis
pers
ion,
m
, m
Transverse normalized emittances from cathode to dump Q=0.7 nC
(PARMELA simulation)
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
BNL 5 Cell SRF Cavity Design
F = 703.75 MHz, E = 20 MeVQ0 ~ 1010, QHOM ~ 103
•The 5-cell cavity was specifically designed for high current, high bunch charge applications such as eRHIC and high energy electron cooling. •The loss factor of the cavity was minimized. •The number of cells was limited to 5 to avoid HOM trapping. •Additionally, HOM power is effectively evacuated from the cavity via an enlarged beam pipe piece 24 cm diameter.
Build: AES
Processed: JLAB
Arrived at BNL
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
Cavity VTA testsThe cavity was processed at JLab. After BCP, Rinsing, and low temp. bake low temp. bake (120 C)(120 C) cavity reached 19 MeV/m at Q0=1010.
19 MeV/m
Ebeam,max 20 MeV
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
HOM measurements
The damping of the Q-values is 2 orders of magnitude. Results well agree with simulations.
Several dipole modes at frequencies below 1 GHz were measured and could be identified by comparison with simulation results
The simulated BBU threshold is of the order of 20 Afor the nominal designed ERL lattice and simulated HOM parameters.GBBU and TDBBU codes were used.Dipole resonances in the RHIC ERL cavity fcu
[MHz] Qcu R/Qcu
[Ω] fFRT
[MHz] QFRT R/QFRT
[Ω] fData [Ω]
QData R/QData [kΩ]
805.1 29,700 0.0 803.4 588 0.1 0.08 810.2 34,000 0.4 808.4 150 1.1 807.8 900 0.17 817.9 34,500 1.2 816.1 136 0.7 0.10 829.2 32,000 0.3 827.0 265 0.2 825.18 370 0.06 851.6 31,000 13.7 849.5 493 11.8 848.99 130 5.8 874.6 31,100 55.1 872.6 379 49.3 18.7 890.2 32,800 43.0 888.1 163 42.0 6.8 897.1 31,900 21.2 895.0 201 22.8 4.6 929.0 42,800 10.1 926.2 104 6.7 0.79 943.8 46,000 5.8 940.7 79 8.6 0.68 957.6 38,500 0.1 956.1 40,370 0.0 958.34 9,500 1.6 963.7 40,700 2.6 962.2 6410 2.6 964.76 3,350 17.0 975.4 45,800 7.9 973.7 2132 8.1 977.15 830 17.2 991.8 54,200 2.4 989.8 1644 2.4 995.46 205 3.9
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
R&D ERL beam parameters
High Current
High Current
High charge
Charge per bunch, nC 0.7 1.4 5
Numbers of passes 1 1 1
Energy maximum/injection, MeV 20/2.5 20/2.5 20/3.0
Bunch rep-rate, MHz 700 350 9.383
Average current, mA 500 500 50
Injected/ejected beam power, MW 1.0 1.0 0.15
R.m.s. Normalized emittances ex/ey, mm*mrad 1.4/1.4 2.2/2.3 4.8/5.3
R.m.s. Energy spread, E/E 3.5x10-3 5x10-3 1x10-2
R.m.s. Bunch length, ps 18 21 31
Operation regimeParameter
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
2-3 MeV
2-3 MeV
20 MeV
20 MeV
20 MeV
2-3 MeV
SC RF GunSC 5 Cell cavity
Beam dump
BPM
DCCT
1MW Klystron
SRF Linac50 kW Transmitter ready to operate
Arc assembly
Quadrupole
Dipole
Tested in
BLD912
Arrived, test this summer
Measured, ready to be
installed
• ERL Enclosure (Vault) was constructed• 5-cell Cavity is being processed and tested at JLAB, arrived in
March, 2008• The dumping of HOM Q-values measured 2 orders of magnitude • 1 MW Gun klystron and 50 kW 5-cell cavity transmitter are installed • Recirculation loop magnets and vacuum system components have
arrived• Injection dipoles are under magnetic measurements• Gun drive laser is been procured • Gun is under construction at AES
BNL R&D ERL: Status
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
R&D ERL Commissioning Milestones and beyond
Coherent Electron Cooling Proof of Principal Test around 2012
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
Modifications from R&D ERL to P-o-P CEC
• Move SRF Gun, 5cell cavity, loop arcs and injection line from 912 to IR2
• Stretch straight line in order to accommodate cooling section (modulator-undulator-kicker ) ~15 m
• Build and install 7 m undulator
Bldg 912
IR2
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
SC 5 Cell cavity
IR-2 for proof-of-principle for CEC19.6 m
RHIC Beam RHIC Beam
RHIC lattice functions IR2
7 m4 m4 m
electron and ion beams
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
Electron beam lattice functions for CEC PoP test at RHIC
UNDULATOR
Modulator region
Kicker region
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
16.2 16.3 16.4 16.5 16.6 16.7 16.80
0.2
0.4
0.6
0.8
1
7.813 10 4
HistKE1 1
max HistKE1 1 HistKE11 1
max HistKE11 1
16.76416.254 HistKE1 0 HistKE11 0
20 10 0 10 2016.2
16.4
16.6
16.816.765
16.249
KE1
KE11
16.62213.389 Phi1 Phi11
Q=1.4 nC,
100% : dE/E=4.8x10-3, ex/ey=5.6/6.7 um
80% : dE/E=1.3x10-3, ex/ey=5.4/5.6 um
BNL R&D ERL electron beam longitudinal profile
The electron bunch is +/-15 degrees of RF
For CEC: emittance requirements are relax
The energy spread is important
Some injection line modification may be applied
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
CEC proof of principal at RHIC setup
Au bunch intensity 1E09
Z/A 79/197
Energy 40 GeV/n
RMS normalized emittances
2.5 mm-mrad
RMS energy Spread 4E-04
RMS bunch length 66 cm
Beta* 10 m
Electron bunch charge 5 nC (4x1.4nC)
Energy 21.7 MeV
RMS normalized emittances
5 mm-mrad
RMS Energy Spread 0.15 %
Beta* 5 m
pe, CMF 5.0 E09 Hz
Modulator length L1,m 4 m
Number of plasma oscillations
0.256
Ion bunch parameters Electron bunch parameters
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
CEC proof of principal at RHIC setup (cont.)
w 5 cm
Undulator length 7 m
B 1.2 kGauss
Beta_und 1 m
aw 0.555
FEL 18 m
Amplitude gain G =150, Lw 7 m
IBS rate 9 min
Cooling time, beam, 2.6 minutes
FEL parameters Cooling parameters
CEC 2Grp
nL2
Z 2
A
Electron bunches are usually much shorter that the hadron bunches and cooling time for the entire bunch is proportional to the bunch-lengths ratios
bunch CEC ,e
,hThe formula gives very encouraged result
More simulations and accurate studies are under way
Ion bunch: 2.5E-09 secElectron bunch: 50E-12 sec
Kicker length, L2 3 m
Cooling time, local, minimum 0.05 minutes
4th Electron-Ion Collider Workshop, 4th Electron-Ion Collider Workshop, Hampton University, May 2008 19-23Hampton University, May 2008 19-23
Plans & ConclusionsPlans & ConclusionsDesign of major ERL components is completed. Hardware components are being manufactured and/or procured.We plan to start commissioning of the R&D ERL in 2009
•First, we develop the straight pass (gun -- 5 cell cavity -- beam stop) test for the SRF Gun performance studies.
•Next, a novel concept of emittance preservation in a beam merger at the lower energy will be tested
•After recirculation loop completed, demonstrate energy recovery of high charge and high current beam
The prototype will serve as a test bed for studying issues relevant for very high current ERLs (since 2010)Proof of principle coherent electron cooling ions in RHIC at ~ 40 GeV/n is feasible with existing R&D ERL parameter and should be demonstrate around 2012