the accelerator test facility and optical stochastic cooling r&d hepap aard sub panel vitaly...
TRANSCRIPT
The Accelerator Test Facility and Optical Stochastic Cooling
R&D
HEPAP AARD Sub panelVitaly Yakimenko
Brookhaven National Laboratory
February 15, 2006
BNL Accelerator Test Facility -
ATF
The ATF is a proposal-driven, advisory committee reviewed USER FACILITY for long-term R&D into the Physics of Beams.
The ATF serves the whole community: National Labs, universities, industry and international collaborations.
ATF contributes to Education in Beam Physics. (~2 PhD / year)
In-house R&D on photoinjectors, lasers, diagnostics, computer control and more (~3 Phys. Rev. X / year)
Support from HEP and BES.
The ATF features: High brightness electron
gun 75 Mev Linac High power lasers beam-
synchronized at the picosec level (TW level CO2 laser)
4 beam lines + controls
Main facility results/directions:
1. High brightness injectors: 2. Electron beam diagnostics3. Development of a picoseconds
Terawatt CO2 laser4. Generation of the short bunches on all
scales5. Experimental demonstration of various
advanced acceleration techniques6. Free Electron Laser experiments
Facility (concept, developments and name are copied) 24 PhD students graduated
Why we need better emittance
ICAIFEL
ThomsonX-ray source
HGHG
1995 1998 2001 2004
STELLA
5 m
2 m
1 m
0.5 m
VISA
Dielectric WFA
Smith Purcell
experiment
First 1.6 cell gun
Microbunching
Mg cathode Mg cathode
Gun IV
SASE @1m
Plasma WFA
Design of the 1.6 cell gun is adopted in more then a dozen facilities
To match FEL or accelerating optical and electron beams; or to transport through small (high frequency) accelerating channel
ATF Terawatt CO2 Laser Story (past and present)
InverseCherenkovaccelerator IFEL
accelerator
ThomsonX-ray source
HGHG
1995 2000 2005 2010
STELLA
EUV source
Ion andProtonsource
ResonantPWA
SeededLWFA
LACARAPASER
3 TW
300 GW
30 GW
3 GW
Nonlinear Thomsonscattering
Near-term plan (2-3 year scale)• Multi-bunch plasma wake field acceleration
experiments to demonstrate a high transformer ratio and a mono-energetic accelerated e-beam.
• Generation of ion, neutron, and proton beams with MeV energies from a foil and gas jet with a multi-Terawatt CO2 laser.
• Upgrade of the CO2 laser to the 20TW level and experimental studies of advanced accelerators and radiation sources in a strong-field relativistic regime.
• Operation and characterization of a visible SASE FEL in the amplifier regime.
• Continued improvement of electron beam brightness utilizing a photoinjector laser upgrade, advances in beam diagnostics and beam compression.
ATF Budget Analysis: FY03/07 ($K)PROJECT FY03 FY04 FY05 FY06(cur) FY07(proj)ATF Ops $1,680$1,800$1,800$1800 $1,990ATF Equ $200 $200 $200 $200 $220ATF (BES) $500 $500 $500 $500 $500
Totals: $2,380$2,500$2,500$2,500 $2,710
ATF is supported by•LDRD at different levels from its formation (currently 120K$/year) •HEP DOE from 1991 (directly)•BES DOE from 1991 (indirectly) from 2002 (directly)
ATF continues to be staffed at the critically low level: Recent reduction in the scientific personnel by 2 has negatively affected facility efficiency.
Increase in staff is needed to improve support of experiments, increase run time and make users programs more efficient.
ATF Org. chartDOE BES
B. Gibbs, ALD –(Contact)
S. DawsonChair, Physics Department
V. YakimenkoDirector ATF, Accelerator
External program committeeS. Chattopadhyay, Chair
M. WoodleEngineer Mechanical
M. MontemagnoEngineer Electrical
I. Pogorelsky, Physicist, Laser
I. PavlishinEngineer,
Laser
D. DavisTechnician
Mech./Laser
M. BabzienEngineer,
Laser
K. KuscheEngineer,
Safety
DOE HE,S. Aronson, ALD – (Contact)
R. MaloneSr. Tech. Architect
Computer Control
K. BergesenSoftware designer
A. Karostoshevsky,Mechanical designer
K. TuohyGroup Secretary
D. StolyarovResearch Associate,
Laser
T. CorwinTechnician
Electr./Mech.
R. PalmerATF Program Director
Story of one short experiment …Beam break up was noticed during beam compression studies by UCLA.
Beam before final compression Beam after final compression
EE~100 fs ~1 ps
Time resolved optical spectrum of the plasma emission was measured to characterize plasma #31 density USC & ATF
ne [
cm-3.]
time delay [ns]1
10
100
1000
10000
100000
0 100 200 300
Filter cutoff [microns]Filter cutoff [m]
CTR
[a.u
.]
CTR spectrum was measured by S. Banna #30 using UCLA bolometer #26 and THz filters from STI #32 to characterize beam
Beam was sent through plasma channel ATF & STI #32 in the first PWF double beam experiment
E
Experiments are very sophisticated and very efficient sharing of the resources between experimental groups is essential
Basic idea of OSCStochastic Cooling Optical Stochastic Cooling
2d sn eN3
is
l
NN
20 ideald dn nIn practice In practice time is amplifier limited
~ 12 m => power limited cooling time~1 hr with 16 W; bandwidth limited ~11 sec!
~ 5 cm => ideal bandwidth limited cooling time~2.5 hrs.
sample length ~10 cm
sample length ~50 m
5 main components of OSC
• Pair (per ring) of super conductive wigglers
• Optical amplifier (Optical Parametric Amplifier (OPA):
• Pump source for OPA • Lattice modification• Diagnostics
3 cm length crystal → intensity gain 3 105
Optical Parametric Amplifier OPA
Parametric process is photon interaction in which one high frequency photon is annihilated and two lower frequency photons are created, i.e.: (pump) =(signal) +(idler) where photon energy is conserved. In addition, photon momentum is conserved by the wave vectors: k(pump) =k(signal) +k(idler) .
OPA test at ATF• Basic parameters of the crystal• Bandwidth of the amplifier• Phase fidelity
Future development ATF ?• acquire X-band technology (extreme
beam compression, diagnostics, testing of X-band devices, high gradient…)
• Polarized Positron Source (PPS) with linac and CO2 laser R&D for ILC
• upgrade of CO2 system to 300TW level and high field experiments
• energy upgrade to 1GeV with energy recirculator (PWFA experiments, PPP)
Electron cooler in RHIC IP12
Number of particles in the ion bunch (as a result of “burn-off”,
recombination, cooling, IBS)
Integrated luminosityis about the same as without suppressionof recombinationdue to reductionin cooling force
<L>=7e27 <L>=6e27
<L>=6e27
Recombination: OFF Recombination: ONWigglers: OFF
Recombination: ONWigglers: ON
Average store Luminosity withoutCooling 6e26
20 MeV High Current High Brightness R&D ERL : layout in 912
Ampere Class Cryomodule
“Single mode cavity”:HOM (R/Q)Q~2*103 Ohms monopoles, ~2*105 Ohms/m dipole modes.BBU threshold current > 2 amperes
SRF Gun – critical element
CathodeisolationValves
Cathodeinstallationassembly
Beam lineisolation valve
Top cover withfacilities feedthru
Cavityassembly
InternalHelium dewar
Adjustable supports
Magnetic andthermalshielding
HOM Ferrite
Vacuum vesselPowercouplers
InsulatingVacuum Port
Gain in Emission mode:polycrystalline electronic grade, Ip=100nA, 300K
0
10
20
30
40
50
60
0 1 2 3 4 5 6
MV/m
Em
issi
on
gai
n
2keV 3keV 4keV 5keV
Gain of 50, still increasing W/ field, further investigation underway
Gain in Emission mode From Hydrogenated samples
Natural Diamond-Ip=100nA,T=300K
0
5
10
15
20
25
30
35
0 0.5 1 1.5 2
Field in MV/m
Gain
2keV 3keV 4keV 5keV