High current cyclotron for ADSS : Efforts at VECC

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High current cyclotron for ADSS Efforts at VECC

• P. Sing Babu
• A. Goswami
• V. S. Pandit
• Variable Energy Cyclotron Centre
  Kolkata-700 064

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A Possible Configuration of Cyclotrons for ADS
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Plan of the talk

• Magnet design of 10MeV cyclotron
• Study on buncher
• Design of spiral inflector
• Design of central region
• Status of the project
• Future plans

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Parameters of Injector Cyclotron
V.S. Pandit, P.S. Babu NIM A523 (2004) 19-24
A. Goswami, P.S. Babu V.S. Pandit NIM A 562
(2006)34
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Magnet design
Dimensions of the magnet and the properties of
E.O. were first determined by hard edge
approximation method. Finally 3D computer code
was used for optimization. Shape of magnet
sector was obtained by iterative process. Design
of central plug geometry is very
vital Optimisation of central plug is in
progress.
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Magnet design
3D MAGNET code was used to calculate the
isochronous magnetic field. To improve accuracy,
we have used 1/8th model. Hill was divided in
many parts to give appropriate mesh sizes in
different regions.
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Magnet design
Optimized angular sector width as a function of
radius
Comparison of calculated and required isochronous
magnetic field.
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Orbit properties
Properties of the equilibrium orbit were
optimized using code GENSPEO.
Frequency error ???? (?0-?)/? as a function of
the radius.
Integrated phase shift with radius. The phase
excursion is within ? 10
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Orbit properties
Variation of radial and axial tunes with radius.
Dotted curves represent the analytical results.
Equilibrium orbits for different energies.
Separation between the last two orbits is 1.8
cm.
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Optimized parameters of the magnet
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Injection system
Ion source LEBT Buncher Spiral inflector
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Ion Source
L100 mm, D90 mm, 2.45 GHz, 1.2 kW
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Extraction
?nrms 0.04? mmmrad
Electrodes 8mm 10mm 10mm
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Buncher simulation

• We have used disc model.
• CW beam is divided into N no. of disc with width
  ltlt ??.
• Drift length is also divided in small interval L
  / d
• Space charge forces are calculated at each
  interval.

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Results Optimum buncher parameters
L 100 cm
Dependence of B. E. on drift length for various
values of beam current
B.E. as a function of buncher voltage for
different beam current
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Results Optimum buncher parameters
Buncher effectiveness at different beam current
Required drift length L and buncher Voltage Vb
for different beam current
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Results Beam distribution at the time focus
I10mA
Density distribution at time focus with and
without space charge
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LEBT and Sinusoidal buncher
Total length 2.8m
SOL1 40cm, 3.2kG SOL2 40cm, 3.0kG
PH2 8020 Slit 5mm 99.60.4
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Beam envelope
Maximum drift distance available for the buncher
100 cm. We have taken care the variation of
beam radius along drift length. We have taken
care that the beam waist is formed at the same
point as that of a cw beam.
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Parameters of the buncher
f 42MHz Vi 100keV Vb5kV L 0.6-0.8 m
Electrode length 45 mm Gap 5mm Chamber
diameter50cm
under fabrication
Buncher location plays an important role
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Spiral Inflector

• To optimize the initial conditions of the beam to
  get the desired output beam properties.
• To optimize the orbit centering of the injected
  beam into the central region.

3D sketch of the infector
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Spiral Inflector
Optimized parameters
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Optical properties
Computer codes used to get the geometrical shape
and electric field distributions in the inflector
are CASINO INFLECTOR
RELAX3D
computed electric field along the central
trajectory.
Paraxial trajectories
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Beam envelope in Spiral Inflector
Envelope around the central ion trajectory
Phase plots in the horizontal and vertical planes.
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Central region
It is designed in such a way that the orbit
center of the injected beam must converge to the
machine center after few turns.
All calculations of the beam centering have been
performed with following parameters
Injection energy 100keV Dee Voltage 125kV Dee
and dummy-dee gap W2cm, Dee height H 3cm
Electric field in Dee
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Central region
Accelerating gaps and optimised orbits for
protons (Radial width ? 4 mm, phase
acceptance ? 150 of rf .)
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Beam Envelope
K-V beam envelope equation in radial and vertical
direction
?r ?z calculated from equilibrium orbit data
We have included the electrical focusing force in
axial direction
Axial tune as a function of radius
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Beam Envelope
Variation of radial and axial beam envelopes
along the accelerated orbit up to 16 turns
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Extraction

• Turn separation _at_10 MeV
• Re 65cm VD125kV
• ?R (acceleration) 24.5 mm
• ?R (?E initial) -0.4 mm
• ?R ( Phase ? 300) - 13.0 mm
• ?R (LSC .18MeV) - 5.0 mm
• Effective turn separation
• ?R 6.0 mm _at_ 5mA
• ?R 0.77mm _at_ 8mA

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Status of the Project
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(No Transcript)
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Status of the Project
Assembly work of the injection system
completed Testing of the ion source have been
done Extracted beam current at faraday cup 120
? A
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Roadmap for the Future
1. Design optimization of central region 2.
Simulation of space charge effects in spiral
inflector
3. Design and analysis of
resonators (HFSS) Electromagnetic
thermal analysis 4. Design optimization of
the extraction system
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Thank You