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PROTON LINAC FOR INDIAN SNS
Vinod Bharadwaj, SLAC
(reporting for the Indian SNS Design Team)
CENTRE FOR ADVANCED TECHNOLOGY, INDORE
• DAE lab, SLAC size in people, area• New lab built 1987 for accelerator & laser R&D • Presently has 450 MeV electron ring (INDUS-1)
for synchrotron light R&D, accelerators for industrial use R&D
• In the process of building 2.5 GeV synchrotron radiation facility (INDUS-2), to start operations in 2004
CENTRE FOR ADVANCED TECHNOLOGY, INDORE
• CAT is the lead $50M collaboration with LHC to build superconducting correction magnets
• Has a lot of internal expertise in building equipment for accelerators
• Indian Government is interested in accelerator facilities and international collaborations (meeting in Delhi in Nov 2003, where this was emphasized in person by the Secretaries of DST and DAE)
INDIAN INTEREST IN HIGH INTENSITY PROTONS
• Indian Government is interested in protons– Accelerator Driven Sub-critical Systems
• burning thorium for energy production
– Accelerator Driven Transmutation of Waste
• Indian Spallation Neutron Source– Part of long range plan– Basic research + ADS R&D– 100 kW power initially– Injector is 100 MeV proton linac
Accelerator Driven Sub-critical Systems
ADSS MOTIVATION
CONCEPTUAL ADSS FACILITY
ISNS Layout
Figure 1. General schematics of the 100 MeV linac
4.5 MeV 100 MeV 50 keV
1 GeV Proton Synchrotron
Ion Source
LEBT & Chopper
RFQ MEBT & Chopper
DRIFT TUBE LINAC Long. Ph. Sp. Painting
Energy
Trans. Ph. Sp. Painting
Spallation Target
ISNS Parameters
Design Specifications of 100 MeV H– Linac
Input energy 4.5MeV Output energy 100MeV Beam current 25mA Particles H- Operating mode Pulsed Pulse duration 500sec Repetition rate 25Hz
Linac Design dominated by the need to
Reduce beam losses to reduce heating and activation
Injector needs to be capable CW operation for injection into future SC linac
Injector needs to be upgradeable to higher current for future ISNS upgrade
ION SOURCE
Low Energy Beam Transport
34% of Synch period (chopped off)
66% of Synch period (Injected)
25 mA Design current
500 Sec 605 micro pulses at Synch RF freq.
I
t
Provides transverse phase space matching between ion-source and RFQ
Chops beam for matching into RFQ buckets
Use codes TRACE3D & IGUN for optimization
RFQ Design
• Use design code PARMTEQM for particle transmission and SUPERFISH for cavity design
• Two designs ..– 25 mA, lower vane voltage, lower beam losses , better for higher
duty factor/CW operations– 50 mA for pulsed operations, can use higher vane voltages for
better beam properties– Plan is to build 25 mA first to get experience and then upgrade
to 50 mA when needed
– Calculations show 96.3 % transmission efficiency
PROTOTYPE RFQ
RFQ Design Parameters
MEBT Design Consideration
It is very essential to match the beam from one accelerating structure to the next one to avoid the formation of beam halo and emittance blow up and subsequent beam loss. The MEBT provides necessary matching between RFQ and the following drift tube linac. The matching in three phase planes is studied by TRACE3D. The MEBT section uses four quadrupoles, two RF gaps and a combination of drift spaces for matching in transverse and longitudinal planes. The design goal was to obtain the mismatch factors below 0.01 in all the three phase planes.
Drift Tube Linac
• Use DTL structure for accelerating from 4.5 MeV output of RFQ to 100MeV injection into the SNS proton synchrotron, operating at 350 MHz
• Accelerating gradient ramped from 1.8 MV/m to 2.2 MV/m from tank 1 to tank 2 and then held at 2.2 MV/m
• Possibility to use S(eparated function) DTL structures for the higher (50 MeV) energies. Tradeoff between ease of manufacture and beam quality being calculated
• 7 tanks, tanks 3-7 the drift tubes have face angle for improved shunt impedance
• Drift bore is 1 cm throughout the linac
Drift Tube Linachttp://www.sns.gov/projectinfo/operations/training/lectures/
DTL_101.pdf
DT and Tank details for Tank-1 and Tank-2
TR
BEAM AXIS
DT and Quadrupole details for Tanks-3 to 7
Lq
LDT
RDT
Quadrupole
Drift Tube
Beam Transmission through DTL*** 100 MeV 350 MHz DTL AS INJECTOR FOR INDIAN SNS ***
-1.0
0.
1.0
-13 125 262 400
x (cm) vs. cell no.
-1.0
0.
1.0
-13 125 262 400
y (cm) vs. cell no.
-1.0
0.
1.0
-13 125 262 400
w-ws (MeV) vs. cell no.
Beam Phase Space at End of DTL*** 100 MeV 350 MHz DTL AS INJECTOR FOR INDIAN SNS ***
ncell = 327 plot#= 343 Zposition= 7400.961
-.015
-.008
0.
.008
.015
-1.000 -.500 0. .500 1.000Xp vs. X -.015
-.008
0.
.008
.015
-1.000 -.500 0. .500 1.000Yp vs. Y
ngood= 9701
-1.000
-.500
0.
.500
1.000
-1.000 -.500 0. .500 1.000Y vs. X -1.000
-.500
0.
.500
1.000
-90.0 -45.0 0. 45.0 90.0E-Es vs. Phi-Phis
Es= 100.498 Ps=-30.0
High power pulsed klystron
• Frequency of operation 350MHz +/- 2.5MHz
• Output peak power 1MW or 2MW• Output RF pulse duration 700
microsecs• Gain 43dB• Maximum drive power 200W• Efficiency 60 %• Output waveguide WR 2300• Focusing Electromagnet
CONCLUSION
• India has ambitious plans for high intensity proton beams, for SNS & ADSS
• A design for a 100 MeV, 25-50 mA H-minus linac exists
• SNS project approved in principle and design efforts are underway