potential cern facilities to study proton-driven plasma acceleration
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potential CERN facilities to study proton-driven plasma acceleration
Frank ZimmermannMunich MPI, 9 December 2008
CTF-3
existing accelerator chain (LHC beam)
PS booster
PS SPS LHC
final momentum [GeV/c] 2.1 26 450 7000protons/bunch [1011] 17 1.3 1.15 1.15rms longitudinal emittance [eVs] 0.11 0.03 0.06 0.2 (0.08*)rms bunch length [ns] 143 1 <0.5 0.25 (0.16*) relative rms energy spread [10-3] 0.32 1 0.3 0.11 (0.07*)rms transverse emittance [mm] 2.5 3.0 3.5 3.75bunch spacing [ns] N/A 25 25 25 # bunches / cycle 4 (4 rings) 72 288 2808cycle time 1.2 s 3.6 s ~22 s 5-10 h?
* w/o longitudinal blow up in the LHC1 ns = 30 cm, 3x10-4 ns = 100 mm
PSB
SPSSPS+
Linac4
(LP)SPL
PS
LHC / SLHC DLHC
Ou
tpu
t en
ergy
160 MeV
1.4 GeV4 GeV
26 GeV50 GeV
450 GeV1 TeV
7 TeV~ 14 TeV
Linac250 MeV
(LP)SPL: (Low Power) Superconducting Proton Linac (4-5 GeV)
PS2: High Energy PS(~ 5 to 50 GeV – 0.3 Hz)
SPS+: Superconducting SPS(50 to1000 GeV)
SLHC: “Superluminosity” LHC(up to 1035 cm-2s-1)
DLHC: “Double energy” LHC(1 to ~14 TeV)
Proton flux / Beam power
present and future LHC injectors
PS2
Roland Garoby, LHCC 1July ‘08
layout of new LHC injectorsSPS
PS2, ~2017
SPL,~2017
Linac4~2012
PS
R. Garoby, CARE-HHH BEAM07, October’07; L. Evans, LHCC, 20 Feb ‘08
R. Garoby, LHCC 1 July 2008
ID WBS Task Name
1 Linac4 project start
2 2 Linac systems
3 2.1 Source and LEBT construction, test
4 Drawings, material procurement
5 2.2 RFQ construction, test
6 2.4 Accelerating structures construction
7 Klystron prototypying
8 2.6.2 Klystrons construction
9 2.6.1 LLRF construction
10 2.7 Beam Instrumentation construction
11 2.8 Transfer line construction
12 2.9 Magnets construction
13 2.10 Power converters construction
14 5 Building and infrastructure
15 5.1 Building design and construction
16 5.2,3,4 Infrastructure installation
17 3 PS Booster systems
18 3.1 PSB injection elements construction
19 3.2 PSB beam dynamics analysis
20 4 Installation and commissioning
21 4.1 Test stand operation (3 + 10 MeV)
22 4.2 Cavities testing, conditioning
23 Cabling, waveguides installation
24 Accelerator installation
25 Klystrons, modulators installation
26 Hardware tests
27 Front-end commissioning
28 4.5 Linac accelerator commissioning
29 Transfer line commissioning
30 PSB modifications
31 4.6 PSB commissioning with Linac4
32 Start physics run with Linac4
01/01
01/05
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q12007 2008 2009 2010 2011 2012 2013 2014
injector upgrade schedulesynchronized with LHC IR upgrades
LHC IR phase 1
LHC IR phase 2
2013: PSB with linac4
2017: SPL+PS2
upgraded accelerator chain (LHC beam)
SPL PS2 SPS LHCfinal momentum [GeV/c] 5 50 450 7000protons/bunch [1011] 2.5x10-4 4 4 4rms longitudinal emittance [eVs] 7.3x10-7 0.05 0.06 0.2 (0.08*)rms bunch length [ns] 1.9x10-4 1 <0.5 0.25 (0.16*) relative rms energy spread [10-3] 0.18 1 0.3 0.11 (0.07*)rms transverse emittance [mm] 0.35 3.0 3.5 3.75bunch spacing [ns] 2.8 25 25 25 # bunches / cycle 200,000 144 288 2808cycle time 20 ms 2.4 s ~13 s 5-10 h?
* w/o longitudinal blow up in the LHC1 ns = 30 cm, 3x10-4 ns = 100 mm
phase space at SPL exit
M. EshraqiA. Lombardi
intermediate conclusions the only proton beam which is naturally “short” is the one
from the SPL, ~60 micron rms length, with 2.5x107 protons / bunch and available at the earliest in 2017 the beam from the SPS must be compressed by a factor
10,000 to obtain rms bunch lengths of 100-200 mm equilibrium bunch length scales with the inverse 4th root
of RF voltage and with the 4th root of the momentum compaction factor
four other possibilities come to mind: rapid change in momentum compaction factor
followed by bunch rotation in mismatched bucket or transverse deflecting cavity?! damping by intrabeam scattering below transition?! coherent electron cooling?!
mismatch
pulse fast quadrupolesto changemomentum compaction, and quickly raise RF voltage
bunch
shape of linear rf bucket
z
d
extract after ¼ synchrotron oscillation when bunch length is minimum
bunch length scales with the square root of pulsed momentum compaction factor
initial momentum compaction ac,initial ~ 0.01 we may hope for ac,new ~ 10-6
initial RF voltage ~ few MVwe may hope for final RF voltage ~ 10x higher
→ expect compression by factor 2 x 10-2 /Sqrt(10) ~ 0.006 ~ 1/160
transverse deflecting cavity+bending system
transverse deflecting cavity
drift
bendingsystem?
can something like this work?
idea is to convert transverse size into longitudinal size
(above schematic ignores x-dependent energy change fromcrab cavity)
can the plasmawave excited by crabbed beam be used for e- acceleration?
shortbunch!
or transverse crab cavity followed by “slit”?
coherent e- cooling
CeC proof-of-Principle experiment at RHIC in 2012
damping times in hours:
promise of 1-hr damping time at 7 TeV!
V. Litvinenko, Y. Derbenev
interesting, but still too small for our purpose
final conclusion
to get “high-energy” proton bunch lengths below 1 mm,
we can use the beam from the SPL, or we need strong cooling or bunch compression or an x(y)-z 4/6-D emittance exchange transformation or a combination thereof
appendix: thoughts on scattering limits and chances
• scattering limits and maximum energy reach of plasma accelerators
• the return of fixed target experiments?
scattering limits and energy reach• at the plasma-acceleration WG of CLIC08 Andrei
Seryi and Tor Raubenheimer reported that 500 GeV acceleration in a plasma was possible, but that 1.5 TeV was excluded by Coulomb scattering – this seemed odd at first glance since Coulomb scattering gets weaker at higher energy
• scattering limits were previously looked at by Montague & Schnell (1985) and Katsouleas & Dawson (1987)
A. SeryiCLIC08 workshop, Plasma wakefield acceleration working group, CERN, Oct. 2008
B.W. Montague, W. SchnellMultiple scattering and synchrotron radiation in the plasma beat wave accelerator.2nd Int. Workshop on Laser Acceleration of Particles, Los Angeles, CA, Jan 7-18 Jan 1985, AIP Conf.Proc.130:146-155,1985.
T. Katsouleas, J.M. Dawson Plasma acceleration of particle beams. 1987. AIP Conf.Proc.184:1798-1828,1989.
22/1
2 1
ds
d
ds
d
2/1
22/3 1
final
d
d
multiple scattering from my memory
indeed the normalized emittance grows as the square root of the finalenergy, but no hard limit in energy reach
to avoid this limit the b function must increase less than with the the square root of energy (e.g. tapered plasma density)
scaling of the multiple scattering limit
bremsstrahlung
most important vacuum limit at high energy e+ or e- machines
this effect would suggest that the total distancetravelled through the plasma cannot be more than one or a few radiation lengths
for example X0~10 m for 4x1022 e/cm3
using the rough estimate of 30 GV/m for 1x1017e/cm3 this gives an ultimate energy of ~200 TeV
0
2ln
0X
X
eEE
nuclear interaction of protons with plasma?
similar magnitude as radiation length
variation with beam energy?
return of fixed target experiments
since extremely high gradients are feasible with plasmas but the collision of two such beams may be difficult to achieve, could fixed target experiments become attractive again? Pantaleo Raimondi
in particular they could be interesting for proton driven plasma accelerators with a single proton beam, a single stage, and very high proton and electron energy;possibly high luminosity
experiment might be different from present colliders
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