small isochronous ring (sir) project at nscl, msu: first
TRANSCRIPT
Eduard Pozdeyev
Small Isochronous Ring (SIR) project at NSCL, MSU: first experimental results
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Outline
IntroductionSpecifics of Space Charge effects in isochronous cyclotrons
Small Isochronous Ring (SIR)Beam parameters and Design
First Experimental ResultsFuture plans
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Isochronous regime in accelerators
0=∂∂Eω 01
2 =−=γ
α pdpdT
Tp
<=>
No synchronous phaseNo longitudinal focusingNo synchrotron motion
Applications:
• Synchrotrons at γtr
• Isochronous Cyclotrons
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High power isochronous cyclotrons
PSI Main Ring Cyclotron:
E = 600 MeVI = 2 mAP = 1.2 MW
1 1 GeVGeV, 10 , 10 mAmA ((10 MW10 MW) cyclotron was proposed for:) cyclotron was proposed for:
•• Waste transmutationWaste transmutation•• AcceleratorAccelerator--driven nuclear reactors driven nuclear reactors •• Neutron and other particle productionNeutron and other particle production
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Specifics of Space Charge effects in isochronous regime
Simulated beam dynamics in PSI Inj. 2, Ib=2 mA, E=5 MeV
Turn 0 Turn 2 Turn 5
Turn 10Turn 7 Turn 20
CYCO: Np=105, Nsc=180 calc./turn
1cm
E
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Small Isochronous Ring: scaling down with energy
BEAM PARAMETERS:
• Low energy (tens of keV)• Light ions: H2
+, D
SC effects scale with energy => low intensity beamRelaxed requirements on diagnostics and Inj./Extr.Simple, low-field magnetsMagnetic Field is strong enough to avoid stray field problem
• Small-scale, inexpensive project• Opportunity to do precise experiments
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Schematic view and main parameters
CHOPPER
INFLECTOR
DEFLECTORFFC
Beams H2+ or D
Energy 0-30 keV
νx, νy 1.14, 1.11
αp 1.0
T 4.5 µsec
C 6.57 m
Nturns 30
Ipeak 0-100 µA
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Comparison to large-scale accelerators
35hωγI
AQSpace charge effects in the
isochronous regime scale as
SIR: Ip=20 µA,
PSI Inj.2: 2 mAPSI Ring Cyc: 8.5 mA
Equiv. to
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Bunch break-up in SIR (simulations)
TURN 0
Ip=20 µAE=23.5 keVtb=200 nsecε=50 π⋅mm⋅mrad
TURN 4
TURN 12
TURN 20
TURN 8
TURN 16
CYCO: Np=3⋅105
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MAY, 2003OCTOBER, 2003 ION
SOURCE
RING
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Dipole magnets
B 1000 GR 450mmBend 90degEdge 26degGap 71mmWeight 250kgPower 750W
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Other subsystems
Steering and QuadrupoleCorrectorsInjection-Extraction
Pulsed electrostatic deflectors
Vacuum systemAl vacuum chamber in the dipolesP=10-8 – 10-7 Torr
DiagnosticsWire scanners2 Phosphor screensFast Faraday Cup (Z=50 Ω)
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First beam in the ring
CHOPPERINFLECTOR
DEFLECTOR
V
VARIABLEDELAY
CHOPPER
INFLECTOR
DEF. t
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Betatron tunes
νx=1.142 (1.140, 1.143) νy=1.110 (1.110, 1.128)
MeasuredCalculated in the measured magnetic fieldCalculated in the TOSCA-generated field
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Beam life-time in the ring
0
10
20
30
40
50
0 10 20 30 40
TURN #
I (nA
)
120)(N
eNI−
∝
Equivalent average pressure 2.5e-7 Torr.
Measured pressure1.2e-7 Torr.
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First indication of space charge effects
Radial beam profile
MEASURED
SIMULATED(CYCO)
2.5
10.5
6.5
14.5
I=20 µAE=17 keVT=1 µsec
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First indication of space charge effects (cont’d)
-
+
E1
E2
E2 > E1
y01.72 0 =−≈
ηθ y
%52 =−
=η
δ βxxEE
7.1°
CYCO: δE/Erms= 1.2% δE/Emax=11.5%
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Longitudinal bunch distribution measured by the Fast Faraday Cup (01/09/2004)
Iarc=1.1 A (? Ibeam=15-20 µA ?), E=24.6 keV, H2+
1 11 3222
100ns15 cm
Iarc=0.25 A (? Ibeam=6-8 µA ?)
1 11 22 32
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Time-line
Fall 2000 – Proposal to build SIR
Sep 2001 - Ion source tested
Nov 2002 - First magnet assembled, mapped
Apr 2003 – Beam through injection line, ¼ of ring
Oct 30, 2003 – One turn in the ring
Nov 2003 – More than 200 turns in the ring
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Future plans
Phase I: Winter-Spring 2004Isochronous regime, longitudinal beam dynamics, Ip=20 µA (δνL=0.05)
Phase II: (?)Non-isochronous regime, transverse and longitudinal beam dynamics, I=100 µA(δνL = 0.25), will include simple RF system
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Acknowledgments
Special thanks: A. Rodriguez, F. Marti, R.C. York
J. Bierwagen, D. Cole, D. Devereaux, R. Fontus, S. Hitchcock, D. Lawton, D. Pedtke, D. Sanderson, J. Wagner, A. Zeller, R. Zink
Personnel of the machine shop, welding shop, electronic shop, support group, computer department, designers and detailers.