Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz 1 LHeC Recirculator with Energy Recovery – Beam Optics Choices Alex Bogacz in collaboration with Frank Zimmermann and Daniel Schulte Accelerator Seminar, CERN, Oct. 7, 2010
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LHeC Recirculator with Energy Recovery – Beam Optics Choices
LHeC Recirculator with Energy Recovery – Beam Optics Choices. Alex Bogacz in collaboration with. Frank Zimmermann and Daniel Schulte. Energy Recovery Recirculating Linacs - Motivation. - PowerPoint PPT Presentation
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Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 1
LHeC Recirculator with Energy
Recovery – Beam Optics Choices
Alex Bogacz
in collaboration with
Frank Zimmermann and Daniel Schulte
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 2
Energy Recovery Recirculating Linacs - Motivation
Future high energy (multi-GeV), high current (hundreds of milli-Amperes) beams would require gigaWatt-class RF systems in conventional linacs - a prohibitively expensive proposition. However, invoking energy recovery alleviates extreme RF power demands; required RF power becomes nearly independent of beam current, which improves linac efficiency and increases cost effectiveness.
Energy recovering linacs promise efficiencies of storage rings, while maintaining beam quality of linacs: superior emittance and energy spread and short bunches (sub-pico sec.).
RLAs that use superconducting RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each particle to pass several times through each high-gradient cavity.
GeV scale energy recovery demonstration with high ratio of accelerated-to-recovered energies (50:1) was carried out on the CEBAF RLA (2003)
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 3
Recirculating Linear Accelerator (RLA) configurations
p-60, p-140 (100), erl
Existing ER RLA’s (Jlab’s FEL & CEBAF ER Exp)
Multi-pass linac Optics in ER mode
Choice of linac Optics - 1300 FODO (1300 vs 1500)
Choice of quad gradient profile in the linacs (wake-field effects)
Choice of Arc Optics -1350 FODO vs FMC (Flexible Momentum Compaction )
Arc Optics Choice - Emittance preserving lattices
Various flavors of FMC lattices in the second stability region (Im. t, DBA, TEM)
Emittance dilution & momentum spread due to quantum excitations
Magnet apertures
Overview - Design Choices
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 4
RLA Configurations
. Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 5
LHeC Recirculator with ER
10 GeV/pass
Linac 1
Linac 2
Arc1, 3, 5 Arc 2, 4 Arc 6
10 GeV/pass
LHC
IP
0.5 GeV
60.5 GeV
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 6
CEBAF - ER Experiment (2003)
Modifications include the installation of:
RF/2 path length delay chicane
Dump and beamline with diagnostics
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 7
“1 pass-up / 1 pass-down” Operation
55 MeV 555 MeV
55 MeV 555 MeV
555 MeV1055 MeV
555 MeV1055 MeV
North Linac
South Linac
Inject
Dump
RF/2 phase delay
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 8
Phase-space degradation?
In an effort to gain a quantitative understanding of the 6D phase space, the following measurements were taken:
Measuring the transverse emittance of the beam in the injector, in each Arc and immediately before being sent to the dump
To characterize the longitudinal phase space, the momentum spread was measured in each Arc
Measure energy recovered beam profiles with a large dynamic range as a way to quantify beam loss and the effect of energy recovery on beam preservation
Measured the RF’s response to energy recovery
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 9
Transverse beam profiles
Beam viewer near the exit of the South Linac
~ 55 MeV Decelerating beam
~ 1 GeV Accelerating beam
500
400
300
200
100
0353025 20 15 105 0
Arb
itra
ry U
nit
s
Distance (mm)
3-wire scanner x 2 beams = 6 peaks
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 10
Beam Profiles of ER Beam
Beam profiles (55 MeV, 1mA beam) measured with a wire scanner and 3 downstream PMTs
(courtesy A. Freyberger)
Each profile (X and Y) is fit
with a function of the form:
F = Gaussian(Core) +
Gaussian(“Halo”) + Background
Quantify beam loss by:
Ratio for X-profile is 1x10-4
Beam loss for Y-profile is
below the noise level
Core
Halo
A
A
X-profileY-profile
5 orders of dynamic
range
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 11
RF Response to Energy Recovery
0.20
0.15
0.10
0.05
0.00
-0.05
-0.10
-0.15
Vol
ts
350300250200150100500Time(s)
Gradient modulator drive signals with and without energy recovery in response to 250 sec beam pulse entering the RF cavity (SL20 Cavity 8)
250 s
with ERwithout ER
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 12
JLAMP 2-pass FEL with ER
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 13
LHeC Recirculator with ER
10 GeV/pass
Linac 1
Linac 2
Arc1, 3, 5 Arc 2, 4 Arc 6
10 GeV/pass
LHC
IP
0.5 GeV
60.5 GeV
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 14
560
0.5
0P
HA
SE
_X&
Y
Q_X Q_Y560
150
0
50
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
Linac Optics 1300 FODO Cell
phase adv/cell: x,y= 1300
700 MHz RF:
Lc =100 cm
5-cell cavity
Grad = 17.361 MeV/m
E= 555.56 MV
linac quadrupoles
Lq=100 cm
GF= 0.103 Tesla/m
GD= -0.161 Tesla/m
E = 0.5 GeV
2×9 cavities 2×9 cavities
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 15
Linac 1 Focusing profile
18 FODO cells (18 ×18 = 324 RF cavities)
E = 0.5 10.5 GeV
10080
200
0
50
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
quad gradient
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 16
Linac 3 (Linac 1, pass 2) Optics
10080
0.5
0P
HA
SE
_X&
Y
Q_X Q_Y
betatron phase advance
10080
500
0
50
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
E = 20.5 30.5 GeV
min
1ds
L E
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 17
10080
800
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
10080
800
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
Linac 1 multi-pass + ER Optics
10080
800
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y 10080
800
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_
X&
Y[m
]
BETA_X BETA_Y DISP_X DISP_Y
10080
800
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_
X&
Y[m
]
BETA_X BETA_Y DISP_X DISP_Y
10080
800
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_
X&
Y[m
]
BETA_X BETA_Y DISP_X DISP_Y
30.5 GeV
40.5 GeV
20.5 GeV
10.5 GeV
0.5 GeV
10.5 GeV
30.5 GeV
40.5 GeV
50.5 GeV
60.5 GeV
50.5 GeV
20.5 GeV
Accelerator Seminar, CERN, Oct. 7, 2010
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 18
Linac 2 Focusing profile
18 FODO cells
E = 10.5 0.5 GeV (ER)
10080
200
0
50
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
quad gradient
Accelerator Seminar, CERN, Oct. 7, 2010
Linac 2 multi-pass optics with ER mirror symmetric to Linac 1 (see previous slide)