Eduard Pozdeyev

Small Isochronous Ring (SIR) project at NSCL, MSU: first experimental results

01/16/04 Eduard Pozdeyev 2

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.