Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
D. Kayran, I. Ben-Zvi, D.S. Barton, D. Beavis, M. Blaskiewicz, J.M. Brennan A. Burrill, R. Calaga, P. Cameron,X. Chang, R. Connolly, D.M. Gassner, H. Hahn, A. Hershcovitch, H.-C.Hseuh, P. Johnson, J. Kewisch, R. Lambiase, V.N. Litvinenko, W. Meng, G. McIntyre, T.C. Nehring, A. Nicoletti, D. Pate, J. Rank, T. Roser, T. Russo, J. Scaduto, K.S.Smith, T. Srinivasan-Rao, N.W. Williams, K.-C. Wu,
V. Yakimenko, K. Yip, A. Zaltsman, Y. Zhao, Brookhaven National Laboratory, Upton, NY, USA
H.P. Bluem, A. Burger, M. Cole, A. Favale, D. Holmes, J. Rathke, T. Schultheiss, A. Todd,
Advanced Energy Systems, Medford, NY, USA J. Delayen, W. Funk, L. Phillips, J. Preble,
Thomas Jefferson National Accelerator Facility, Newport News, VA, USA
High Current Energy Recovery High Current Energy Recovery
Linac at BNLLinac at BNL
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Outline • ERL prototype
– Goals & Parameters
• Step by Step tests– SRF gun, SRF cavity, beam dump– Future steps:
• return loop for ERL - single and double turns• beam stability and feedbacks tests
• ERL modes of operation– CW and test modes for Navy and DoE– Test relevant for the eRHIC concept
• Conclusion
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
electrons
ions Gun
Linac 1Linac 2
Linac 3
Linac 4Stretcher
Compressor
electrons
ions
ions Beam dump
Linac
EBIS Booster
AGS
RHIC II
Electro
n
coolin
g
http://www.agsrhichome.bnl.gov/eCool/
Electron cooler for RHIC II project
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Goals for ERL R&D program at BNLGoals for ERL R&D program at BNL
• Test the key components of the RHIC II electron cooler: – Au-Au luminosity 7x1027 cm-2sec-1, 10- fold boost in p-p luminosity
• 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 • Two turns - 1 A…..
– test the beam current stability criteria for CW beam currents ~ 1 A • Test the key components for future linac-ring e-p and e-ion collider
eRHIC with luminosity of 1034 cm-2sec-1 per nucleon – 10-25 GeV SRF ERL for eRHIC– SRF ERL based an FEL -driver for high current polarized electron gun
• Test the attainable ranges of electron beam parameters in SRF ERL
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
ERL e-Cooler Prototype
ERL circumference [m] ~ 120 ~ 20 Number of passes 1 1 to 2 Beam rep-rate [MHz] 9.38 -28.15 9.38 – 351.875 for tuning 1 Hz – 1 kHz Beam energy [MeV] 54.677 20 - 40 Electrons per bunch (max) 1011 1011 Normalized emittance [m rad] ~ 50 < 50 RMS Bunch length [m] 0.03 – 0.2 0.05 Charge per bunch [nC] 1.6 – 16 1.4 – 10+ Average e-beam current [A] 0.15 – 0.45 0.02 – 0.5 Efficiency of energy recovery 99.9…% > 99.95% Efficiency of current recovery 99.999.…% > 99.9995%
Main Beam parameters for ERLs at Main Beam parameters for ERLs at BNLBNL
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Shielded vault for ERL prototype in Bldg. 912
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
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
30-35 MeV
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Main ComponentsMain Components
Gun
SRFlinac
Beamdump
Returnloop
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Super Conducting RF 2.5 MeV GunSuper Conducting RF 2.5 MeV Gun with Diamond Amplified Photocathodewith Diamond Amplified Photocathode
Emission enhancement (x 30-80) using a diamond window
Initial conceptual design for a superconducting gun with high quantum efficiency cathode.
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Injection into ERLInjection into ERL
20 MeV
2-2.5 MeV
Lambertson septum
Septum-magnet
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Standard and optimized merging systemsStandard and optimized merging systems
15-20 MeVfrom ERLFrom the SC RF Gun
2.5 MeV
Laser
Separating magnet
SolenoidSolenoid
Standard
Optimized
x y
x y
Laser
E Eo
Eo
;
const no focusing i
i
0; zii
i
0
E Eo
Eo
;
o zf ( )
(no focusing) i
i
0; zii
i
0; zi2i
i
0
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
0
2
4
6
8
10
12
14
0 1 2 3 4 5 6 7Length, m
Em
itta
nc
es
, mm
mra
d
Emittance X
Emittance Y
Emittance X
Emittance Y
Emittances X, Y
Results of Parmela simulation for 1 nC e-bunch from the cathode to the end of the linac: black dashed curve is for a round beam passing without bends; blue curves are for a compensated chicane, red curves are for Zigzag merging system.In contrast with where horizontal emittance suffers some traditional chicane growth as result of the bending trajectory, the Z-system (zigzag) the emittances are equal to each other and are very close to that attainable for the straight pass.
Chicane and Zigzag merging systems
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
The emittance and the dispersion The emittance and the dispersion compensation: compensation:
(Parmela simulation)(Parmela simulation)
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0 1 2 3 4 5 6
x, m
y, m
x, m
y, m,
m
, m
m
S, m
Charge: 1.4 nC/bunchEmittances at Linac enrtance:x ~ 1.7 m, y ~ 1.5 m
Emittances and beam sizes as a function of path length.
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Super Conducting 5-cell 703.75 MHz RF Super Conducting 5-cell 703.75 MHz RF linac linac with HOM dampingwith HOM damping
2K main line
Inner magnetic shield
Cavity assembly
4” RF shieldedgate valve
2K fill line
He vessel
Vacuum vessel
Fundamental PowerCoupler assembly
HOM ferriteassembly
Outer magnetic shield
Thermal shield
Tuner location Space framesupport structure
Vacuum vessel
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
11.2 m3.
7 m
ERL Lattice is very flexibleERL Lattice is very flexible
Lattice of ERL has bilateral symmetry: it comprises of six 60o dipole magnets, twenty five quadrupoles and two solenoids
Lattice functions for the case of zero, positive (2 m) and negotive (-2 m) longitudinal dispersion: Figure shows - and D - functions evaluations along the loop.
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Main features of ERLMain features of ERL• Control of m12 for studying the
transverse stability limits in both horizontal and vertical directions
• Control of longitudinal compaction factor for studying longitudinal dynamics
m12 1x2x sinx
m34 1y2y siny
m56 D
ds
x
x
y
y
ctE / E
s2
m11 m12 ... .... ... x
m21 m22 ... ... ... x '
... ... m33 m34 ... y
... ... m43 m44 ... y '
... ... ... ... m55 m56
... ... ... ... ... m66
x
x
y
y
ctE / E
s1
x
x
return
m11 m12
m21 m22
0
x
comming
Excitation process of transverse HOM
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
• TDBBU, MatTBBU give for ERL with this cavity stability limit: currents up to ~1.8 A (1,800 mA !) for a proper lattice
• We plan to increase M12 in order to measure the TBBU and to compare with predictions by TBBU
Stability of Stability of ERL ERL
(R. Calaga)(R. Calaga)
Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004
Plans & ConclusionsPlans & Conclusions
The design and the construction of the R&D ERL is going according to a very aggressive plan
We plan to start commissioning of the R&D ERL in late 2006/early 2007
The prototype ERL will demonstrate the main parameters of the e-beam required for e-cooling
The prototype will also serve as a test bed for studying issues relevant for very high current ERLs and high power FELs
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