LHeC Linac-Ring Design
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Transcript of LHeC Linac-Ring Design
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 1
LHeC Linac-Ring Design
Alex Bogacz
for the LHeC Study Group
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 2
Linac-Ring LHeC – two options
60-GeV recirculating linac with energy recovery
straightlinac
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 3
hgepp
pb HIN
eL
*
, 1
4
1
highest protonbeam brightness “permitted”(ultimate LHC values)
=3.75 mNb=1.7x1011
bunch spacing 25 or 50 ns
smallest conceivableproton * function: - reduced l* (23 m → 10 m)- squeeze only one p beam- new magnet technology Nb3Sn
*=0.1 m
maximize geometricoverlap factor- head-on collision- small e- emittance
c=0Hhg≥0.9
round beams
average e-
current !
Roadmap to 1033 cm-2s-1 Luminosity
DIS'11, Newport News, April 12, 2011
Frank Zimmermann
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 4
Pulsed linac for 140 GeV
140-GeV linacinjector
dump
IP7.9 km
• linac could be ILC type (1.3 GHz) or 720 MHz• cavity gradient: 31.5 MV/m, Q=1010
• extendable to higher beam energies• no energy recovery• with 10 Hz, 5 ms pulse, Hg = 0.94, Nb = 1.5x109 : <Ie> = 0.27 mA → L ≈ 4x1031 cm-2s-1
0.4 kmfinal focus
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 5
Baseline:Energy Recovery Linac60 GeV, Power 100MW
Linac-Ring Configuration
J. Osborne
LHC p
1.0 km
2.0 km
10-GeV linac
10-GeV linac injector
dump
IP
comp. RF
e- final focus
tune-up dump
0.26 km
0.17 km
0.03 km
0.12 km
comp. RF
10, 30, 50 GeV
20, 40, 60 GeV
total circumference ~ 8.9 km
J. Osborne
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 6
Design Parameters
electron beam LR ERL LRe- energy at IP[GeV] 60 140luminosity [1032 cm-2s-1] 10 0.44polarization [%] 90 90bunch population [109] 2.0 1.6e- bunch length [mm] 0.3 0.3bunch interval [ns] 50 50
transv. emit. x,y [mm] 0.05 0.1
rms IP beam size x,y [m] 7 7
e- IP beta funct. *x,y [m] 0.12 0.14
full crossing angle [mrad] 0 0
geometric reduction Hhg 0.91 0.94
repetition rate [Hz] N/A 10
beam pulse length [ms] N/A 5
ER efficiency 94% N/A
average current [mA] 6.6 5.4
tot. wall plug power[MW] 100 100
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 7
Energy Recovering Linacs (ERL)
High energy (60 GeV), high current (6.4 mA) beams: (384 MW beam power) would require sub GW (0.8 GW)-class RF systems in conventional linacs .
nvoking Energy Recovery alleviates extreme RF power demand (power reduced by factor (1
ERL) ⇨ Required RF power becomes nearly independent of beam current.
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.).
GeV scale Energy Recovery demonstration with high ER ratio (ERL
= 0.98) was
carried out in a large scale SRF Recirculating Linac (CEBAF ER Exp. in 2003)
No adverse effects of ER on beam quality or RF performance: gradients, Q, cryo-load observed – mature and reliable technology (next generation light sources)
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 8
CEBAF ER Exp. 2003
~ 55 MeV Decelerating beam
~ 1 GeV Accelerating beam
0.20
0.15
0.10
0.05
0.00
-0.05
-0.10
-0.15
Volts
350300250200150100500Time(s)
250 s
with ERwithout ER
RF Response to Energy Recovery
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 9
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
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 10
Linac RF parameters
ERL 720 MHz ERL 1.3 GHz Pulsedduty factor cw cw 0.05RF frequency [GHz] 0.72 1.3 1.3cavity length [m] 1 ~1 ~1energy gain / cavity [MeV] 18 18 31.5R/Q [100 W] 400-500 1200 1200 Q0 [1010] 2.5-5.0 2 ? 1power loss stat. [W/cav.] 5 <0.5 <0.5power loss RF [W/cav.] 8-32 14-31 ? <10power loss total [W/cav.] 13-37 (!?) 14-31 11“W per W” (1.8 k to RT) 700 700 700power loss / GeV @RT [MW] 0.51-1.44 0.6-1.1 0.24length / GeV [m] (filling=0.57) 97 97 56
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 11
Required Power & Cryo-load
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 12
The eRHIC-type cryo-module containing six 5-cell SRF 703 MHz cavities.
Model of a new 5-cell HOM-damped SRF
703 MHz cavity.
I. Ben-Zvi
RF cavities
DIS'11, Newport News, April 12, 2011
Ilan Ben-Zvi
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 13
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
720 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
2×8 cavities 2×8 cavities
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 14
Linac 1 Focusing profile
18 FODO cells (18 × 2 × 16 = 576 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
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 15
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
E L E
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 16
Linac 2 Focusing profile
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
DIS'11, Newport News, April 12, 2011
Linac 2 multi-pass optics with ER mirror symmetric to Linac 1
18 FODO cells (18 × 2 × 16 = 576 RF cavities)
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 17
Linac 1 and 2 Multi-pass ER Optics
DIS'11, Newport News, April 12, 2011
60480
800
0
50
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y 60480
800
0
50
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
Linac 1 Linac 2
60.5 GeV
50.5 GeV
40.5 GeV
30.5 GeV
20.5 GeV
10.5 GeV
0.5 GeV
0.5 GeV
10.5 GeV
20.5 GeV
30.5 GeV
40.5 GeV
50.5 GeV
60.5 GeV
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 18
10080
1500
0
50
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
‘weak’ vs ‘strong’ Linac focusing
E = 0.5 10.5 GeV
DIS'11, Newport News, April 12, 2011
Zero quad gradient
10080
1500
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
1300 FODO
/
12.9 /12.7 /x y
cm MeVE
/
1.8 /1.6 /x y
cm MeVE
Wake field effects more severe ~ 8 timesDaniel Schulte
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 19
ERL configuration
DIS'11, Newport News, April 12, 2011
total circumference ~ 8.9 km
Daniel Schulte
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 20
52.35990
150
0
0.3
-0.3
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
Quasi-isochronous FMC Cell
Emittance dispersion
〈 H 〉 avereged over
bends
2 22 ' 'H D DD D
Momentum compaction
56 bend
DM ds D
356 1.16 10 mM
factor of 27 smaller than FODO factor of 2.5 smaller than FODO
3 8.8 10 H m
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 21
52.35990
500
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y52.35990
500
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y52.35990
500
0
0.5
-0.5
BE
TA
_X&
Y[m
]
DIS
P_X
&Y
[m]
BETA_X BETA_Y DISP_X DISP_Y
Arc Optics – Emittance growth
total emittance increase (all 5 arcs): xN = 1.25 × 4.5 m rad =5.6 m rad
Arc 1 , Arc2
6 2 20 2
2, 2 ' '
3N
qC r H H D DD D
TEM-like Optics DBA-like Optics Imaginary t Optics
Arc 3 Arc 4 , Arc5, Arc 6
3 1.2 10 H m 3 8.8 10 H m 3 2.2 10 H m factor of 18 smaller than FODO
DIS'11, Newport News, April 12, 2011
emittance growth due to disruption in the collision 15%-180% (without/with rematch the outgoing optics)
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 22
Alternative Arc Optics BNL FMC Cell
Flexible Momentum Compaction
DIS'11, Newport News, April 12, 2011
Dejan Trbojevic
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 23
Recirculator Magnets
# Field M.Length # Gradient M.Length # Gradient M.Length # Gradient M.Length # Gradient M.LengthLINAC 1 18 2.200 1.000 18 -2.200 1.000LINAC 2 18 2.200 1.000 18 2.200 1.000Arc 1 600 0.046 4.000 60 -3.179 1.000 60 10.515 1.000 60 -11.053 1.000 60 10.535 1.000Arc 2 600 0.089 4.000 60 -6.206 1.000 60 20.529 1.000 60 -21.579 1.000 60 20.568 1.000Arc 3 600 0.133 4.000 60 12.397 1.000 60 17.493 1.000 60 -24.576 1.000 60 17.918 1.000Arc 4 600 0.177 4.000 60 16.462 1.000 60 23.228 1.000 60 -32.633 1.000 60 23.792 1.000Arc 5 600 0.221 4.000 60 29.227 1.000 60 28.904 1.000 60 -40.791 1.000 60 29.667 1.000Arc 6 600 0.264 4.000 60 35.014 1.000 60 34.627 1.000 60 -48.868 1.000 60 35.541 1.000
60.5 GeV LHeC Recirculator: Linac FODO, Arcs FMC optics
Units: meter (m), Tesla (T), T/m
Q2 Q3Dipoles (R=764 m) Q0 Q1
Proposed solution: One type of bending magnets, possibly with different conductors
Two types of quadrupoles, same cross section, different length: Q2 1200 mm, Q0-Q1-Q3 900 mm; possibly with different conductors, radius 20 mm
Davide Tommasini
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 24
Quadrupoles for 10 GeV Linacs
Parameters for Quadrupoles
Number of magnets 72
Aperture radius [mm] 20
Field gradient [T/m] 4.4
Magnetic Length [mm] 500
Weight [kg] 150
Number of turns/pole 18
Current [A] 40
Conductor material Copper
Current density [A/mm2] 1.5
Resistance [mW] 60
Power [kW] 0.1
Inductance [mH] 9
Cooling Air25 cm
Davide Tommasini
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 25
Bending for 60 GeV Recirculator
Magnet Parameters L-R
Beam Energy [GeV] 70
Magnetic Length [m] 5.0
Magnetic field [Gauss] 3300
Number of magnets 6*600
Vertical aperture [mm] 25
Pole width [mm] 80
Number of coils 2
Number of turns/coil 1
Current [A] 2750
Conductor material copper
Magnet Inductance [mH]
0.12
Magnet Resistance [mW]
0.13
Power per magnet [kW] 1
Cooling Air or water
23 cm
Davide Tommasini
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 26
Quadrupoles for 60 GeV Recirculator
Parameters for Quadrupoles
Number of magnets 1440
Aperture radius [mm] 20
Field gradient [T/m] 41
Magnetic Length [mm] 900-1200
Weight [kg]
Number of turns/pole 17
Current [A]
Conductor material Copper
Current density [A/mm2]
Resistance [mW]
Power [kW]
Inductance [mH]
Cooling
35 cm
Davide Tommasini
DIS'11, Newport News, April 12, 2011
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 27
Three-beam IR layout
DIS'11, Newport News, April 12, 2011
Rogelio Tomas
IR with a schematic view of synchrotron radiation – beam trajectories with 5 and 10 envelopes
Half quadrupole with field-free region
Stephan Russenschuck
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 28
The presence of a strong synchrotron radiation has two major implications for the vacuum system:
it has to be designed to operate under the strong photon-induced stimulated desorption while being compatible with the significant heat loads onto the beam pipes.
synchrotron radiation will dramatically enhanced the electron cloud build-up and mitigation solutions shall be included at the design stage.
Photon-induced desorption rate depends on critical energy of the synchrotron
light
E0 = 5.10-4 GeV for electrons, EB is the energy of the beam and R the bending radius
For the Linac-Ring option (bending sections and by-passes), the linear photon flux is expected to be 5 times larger than in LHC.
Vacuum requirements
DIS'11, Newport News, April 12, 2011
Miguel Jimenez
2
431024.1/IE
mWP
10337
o
Bc E
E
ReV
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 29
Scattering of particles on the molecules of the residual gas, dominated by the Bremsstrahlung on the nuclei of gas molecules ⇨ depends on partial pressure, weight of the gas species and radiation length
The beam-gas interactions are responsible for machine performance limitations such as;
reduction of beam lifetime (nuclear scattering)
machine luminosity (multiple Coulomb scattering)
intensity limitation by pressure instabilities (ionization)
Vacuum engineering issues
Pumping
Diagnostics
Sectorization
HOM and Impedance implications
Bake-out of vacuum system
Shielding
Vacuum mitigation
DIS'11, Newport News, April 12, 2011
Miguel Jimenez
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 30
Conclusions
DIS'11, Newport News, April 12, 2011
High luminosity Linac-Ring option ERL
RF power nearly independent of beam current.
Multi-pass linac Optics in ER mode
Choice of linac RF and Optics 720 MHz SRF and 1300 FODO
Linear lattice: 3-pass ‘up’ + 3-pass ‘down’ (single-pass wake-field effects)
Arc Optics Choice Emittance preserving lattices
Quasi-isochronous lattices
Flexible Momentum Compaction
Acceptable level of emittance dilution & momentum spread
Magnet design
Quad and dipole prototypes
Vacuum requirements
Mitigations and engineering issues
Operated by JSA for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
Alex Bogacz 31
Special Thanks to:
DIS'11, Newport News, April 12, 2011
Frank Zimmermann
Daniel Schulte
and
Max Klein