High Current Energy Recovery Linac at BNL
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Transcript High Current Energy Recovery Linac at BNL
High Current Energy Recovery Linac
at BNL
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
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
• ERL prototype
Outline
– 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
Electron cooler for RHIC II project
RHIC II
ions
CompressorGun
ions
electrons
Booster
Linac 2
AGS
Linac 3
ions
electrons
Beam
Stretcher dump Linac 4
http://www.agsrhichome.bnl.gov/eCool/
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
Linac 1
Goals 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
Main Beam parameters for ERLs at BNL
ERL
e-Cooler
Prototype
ERL circumference [m]
Number of passes
Beam rep-rate [MHz]
for tuning
Beam energy [MeV]
Electrons per bunch (max)
Normalized emittance [m rad]
RMS Bunch length [m]
Charge per bunch [nC]
Average e-beam current [A]
Efficiency of energy recovery
Efficiency of current recovery
~ 120
1
9.38 -28.15
~ 20
1 to 2
9.38 – 351.875
1 Hz – 1 kHz
20 - 40
1011
< 50
0.05
1.4 – 10+
0.02 – 0.5
> 99.95%
> 99.9995%
54.677
1011
~ 50
0.03 – 0.2
1.6 – 16
0.15 – 0.45
99.9…%
99.999.…%
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
30-35 MeV
e- 15-20 MeV
Cryo-module
SRF cavity
1 MW
703.75 MHz
Klystron
e2.5 MeV
50 kW 703.75 MHz
system
Control room
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
Main Components
Return
loop
SRF
linac
Beam
dump
Gun
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
Super Conducting RF 2.5 MeV Gun
with Diamond Amplified Photocathode
Initial conceptual design for a superconducting
gun with high quantum efficiency cathode.
Emission enhancement
(x 30-80) using a
diamond window
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
Injection into ERL
Lambertson septum
20 MeV
Septum-magnet
2-2.5 MeV
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
Standard and optimized merging systems
Standard
Laser
x y
From the SC RF Gun
2.5 MeV
Laser
15-20
MeV
from ERL
Separating
magnet
E Eo
;
Eo
const no focusing i 0; zii 0
i
Optimized
z
x y
Solenoid
i
E Eo
;
Eo
o z f ( )
Solenoid
(no focusing) i 0; zii 0; zi i 0
2
i
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
i
i
Chicane and Zigzag merging systems
14
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.
12
Emittances, mm mrad
Emit tance X
Emit tance Y
Emit tance X
Emit tance Y
Emit tances X, Y
10
8
6
4
2
0
0
1
2
3
4
Length, m
5
6
7
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
The emittance and the dispersion compensation:
6
6
5
5
4
4
x, m
3
3
Charge: 1.4 nC/bunch
Emittances at Linac enrtance:
x ~ 1.7 m, y ~ 1.5 m
, mm
, m
(Parmela simulation)
y, m
2
2
m
x,
m
y,
1
0
0
1
1
2
3
4
5
6
S, m
0
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
linac with HOM damping
4” RF shielded
gate valve
HOM ferrite
assembly
Tuner location
2K main line
Space frame
support structure
Cavity assembly
Vacuum vessel
2K fill line
Outer magnetic shield
Thermal shield
He vessel
Inner magnetic shield
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
Fundamental Power
Coupler assembly
3.7 m
ERL Lattice is very flexible
11.2 m
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 ERL
•
•
m12 1x 2x sin x
Control of m12 for studying the
transverse stability limits in both
horizontal and vertical directions
Control of longitudinal
compaction factor for studying
longitudinal dynamics
m34 1y 2y sin y
m56
D
ds
x m11 m12 ...
....
...
x
x
m21
m22
...
...
...
'
x
y ...
... m33 m34 ...
y
y
...
...
m43
m44
...
'
y
ct ...
...
...
... m55 m56
...
...
...
... m66
E / E s2 ...
x
m11 m12 0
x return m21 m22 xcomming
Excitation process of transverse HOM
on High Average Power & High Brightness Beams
Workshop
UCLA, Los Angeles, CA, November 8 – 10 , 2004
x
x
y
y
ct
E / E s1
Stability of ERL
(R. Calaga)
• 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
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004
Plans & 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
Workshop on High Average Power & High Brightness Beams
UCLA, Los Angeles, CA, November 8 – 10 , 2004