Research activities in high current cyclotron development at

Research activities in high current cyclotron development at VECC A. Goswami, P. Sing Babu, V. S. Pandit Variable Energy Cyclotron Centre, Kolkata UFCYC-2012 A. Goswami

Cyclotron path for ADSS UFCYC-2012 A. Goswami 2

Outline • Ion source and LEBT Line • Cyclotron magnet design • Research activities on High current cyclotron Spiral inflector Beam transport line elements Multispecies beam • Conclusions and Future plans UFCYC-2012 A. Goswami 3

High current ion source (2. 45 GHz, 1. 2 k. W) 20 m. A @ 80 ke. V proton beam Plasma chamber: L = 100 mm, D = 90 mm Electrodes: 7 mm 10 mm UFCYC-2012 A. Goswami 4

Injection Line (LRBT) • Two solenoids DCCT Faraday cup & Slit • Steering magnet Dipole magnet Spiral inflector DCCT Slit F/C UFCYC-2012 A. Goswami 5

Injection line; cont. . . At 400 watt power and @ 80 k. V : Beam current on DCCT = 10 m. A, Beam spot of 80 ke. V, 5 m. A on water cooled alumina plate. UFCYC-2012 A. Goswami Beam current on FC = 7 m. A Assembly of dipole magnet and spiral inflector 6

We are here. . . • Ion source and LEBT Line • Cyclotron magnet design • Research activities on High current cyclotron Spiral inflector Beam transport line elements Multispecies beam • Conclusions and Future plans UFCYC-2012 A. Goswami 7

Magnet design (10 Me. V-5 m. A) Primary dimensions of the magnet were first determined by analytical calculations with hard edge approximation. ØHills & valleys treated as bending magnets. ØThin lenses at H-V boundary. A. Goswami, P. Sing Babu and V. S. Pandit; NIM A 562 (2006) 34. UFCYC-2012 A. Goswami 8

Magnet design; random search method Ø Approximated the sector shape by polynomial function of radius Ø Obtained the frequency error as a function of energy using GENSPEO. Ø Minimized frequency error by optimizing the coefficients of the polynomial UFCYC-2012 A. Goswami 9

Magnet design; cont. . Parameter Value Number of sector 4 Hill gap 40 mm Valley gap 500 mm Sector width 16 -34 deg Hill field 1. 5 T Valley field 0. 15 T Extraction radius 65 cm P. Sing Babu, A. Goswami, P. R. Sarma, V. S. Pandit NIM A 624 (2010) 560. UFCYC-2012 A. Goswami 10

We are here. . . • Ion source and LEBT Line • Cyclotron magnet design • Research activities on High current cyclotron; acceptance Spiral inflector Beam transport line elements Multispecies beam • Conclusions and Future plans UFCYC-2012 A. Goswami 11

Central region acceptance K-V beam envelope equations in radial and vertical direction At each gap the energy of the particle is increased by 100 ke. V UFCYC-2012 A. Goswami 12

Acceptance; cont. . . Possible to injected I >10 m. A (5 mm half aperture) A. Goswami, P. Sing Babu and V. S. Pandit; NIM A 562 (2006) 34. UFCYC-2012 A. Goswami 13

Envelope oscillation (cyclotron) Evolution of transverse beam envelopes UFCYC-2012 A. Goswami 14

Envelope oscillation; cont. . . Ø 5 m. A beam can be controlled within 5 mm half aperture in both planes. A. Goswami, P. Sing Babu , V. S. Pandit; Eur. Phys. J. Plus 127 (2012) 47. UFCYC-2012 A. Goswami 15

We are here. . . • Ion source and LEBT Line • Cyclotron magnet design • Research activities on High current cyclotron Spiral inflector; Design and beam dynamics Beam transport line elements Multispecies beam • Conclusions and Future plans UFCYC-2012 A. Goswami 16

Spiral inflector design Inflector It is used to inflect ion beams in a cyclotron Design Parameters: Height A UFCYC-2012 Tilt parameter k A. Goswami Parameter Value Height (A) 8. 6 cm Tilt (k’) 0. 65 Electric field 18. 5 k. V/cm Off centering 4 cm Electrode gap 1. 4 cm 17

Transverse Beam dynamics (Spiral inflector) Hamiltonian for transverse motion of a particle in a spiral inflector Self - potential obeys the Poisson’s equation Uncoupled lattice UFCYC-2012 Ø Coupled lattice ? ? ? A. Goswami 18

Inflector beam dynamics; cont. . . Motions are coupled in inflector Use a rotated coordinate system where the beam cross section is upright • Calculate self field • Infinitesimal matrix • Solve EQM for ds << L 1 2 3 • Recursive sigma matrix UFCYC-2012 A. Goswami 19

Inflector Beam dynamics; cont. . . The input beam should be converging non-axisymmetric with equal emittances. A. Goswami, P. Sing Babu , V. S. Pandit; Eur. Phys. J. Plus (2012) [revision] UFCYC-2012 A. Goswami 20

We are here. . . • Ion source and LEBT Line • Cyclotron magnet design • Research activities on High current cyclotron Spiral inflector Beam line element; Glaser magnet Multispecies beam • Conclusions and Future plans UFCYC-2012 A. Goswami 21

Input beam with unequal emittances Ions from ECR ion source has an initial correlation and unequal emittances in two planes. Glaser magnet UFCYC-2012 A. Goswami 22

Glaser magnet; cont. . . A. Goswami, P. Sing Babu , V. S. Pandit; NIM A 678 (2012) 14. A. Goswami, P. Sing Babu , V. S. Pandit; Physics of Plasmas (submitted) UFCYC-2012 A. Goswami 23

We are here. . . • Ion source and LEBT Line • Cyclotron magnet design • Research activities on High current cyclotron Spiral inflector Beam line element; Elliptical solenoid Multispecies beam • Conclusions and Future plans UFCYC-2012 A. Goswami 24

Elliptical solenoid; Beam matching The elliptic aperture of the solenoid generates an unequal focusing forces in the two transverse planes. For solenoid UFCYC-2012 D(s) = 0 A. Goswami 25

Elliptical solenoid; cont… Ø Third Glaser form a beam waist at a distance ~ 40 cm. Ø Use an elliptical solenoid for beam matching to the inflector. A. Goswami, P. Sing Babu and V. S. Pandit; NIM A 685 (2012) 46. UFCYC-2012 A. Goswami 26

We are here. . . • Ion source and LEBT Line • Cyclotron magnet design • Research activities on High current cyclotron Spiral inflector Beam transport line elements Multispecies beam; New envelope model • Conclusions and Future plans UFCYC-2012 A. Goswami 27

Multispecies beam; New envelope equation Beam from MW ion source consists of p(~80%), H 2+(~15%), H 3+(~5%) UFCYC-2012 A. Goswami 28

Multispecies beam; cont. . . P. Sing Babu, A. Goswami, V. S. Pandit, Phys of Plasmas 18, 103117, (2011). UFCYC-2012 A. Goswami 29

Conclusions Ø Optimized the magnet sector by Random search method. Ø 5 m. A beam can be controlled within 5 mm half aperture in the cyclotron. Ø A non-axisymmetric with equal emittances beam at the inflector entrance is required. Ø Combination of Glaser magnet and an elliptical solenoid can be used for transverse matching. Ø Multispecies envelope equations developed by us are new and very useful. UFCYC-2012 A. Goswami 30

Future Plans v Beam profile measurement with two CCD cameras and associated software. v Testing of the space charge dominated beam inflection with spiral inflector. v Installation of Fast Faraday Cup and Buncher. v Development of PIC code. UFCYC-2012 A. Goswami 31

Team members • • • UFCYC-2012 G. Pal P. R. Sarma C. Nandi S. Roy S. Bhattacharya S. K. Thakur R. C. Yadav S. Srivastava A. Misra Mou Chatterjee A. Goswami 32

Publications on the project [1] Estimation of the space charge limiting current in a compact isochronous cyclotron V. S. Pandit and P. S. Babu; Nucl. Instr. and Meth. A 523 (2004) 19. [2] Behaviour of space charge dominated beam in a high current compact cyclotron A. Goswami, P. Sing Babu and V. S. Pandit; Nucl. Instr and Meth. A 562 (2006) 34. [3] Simulation of beam bunching in the presence of space charge P. Sing Babu, A. Goswami, and V. S. Pandit; Nucl. Instr. and Meth. A 603 (2009) 222. [4] Optimization of sector geometry of a compact cyclotron by random search and Matrix P. S. Babu, A. Goswami, P. R. Sarma, V. S. Pandit; Nucl. Instr. and Meth. A 624 (2010) 560. [5] Behavior of space charge dominated beam during longitudinal compression in a bunching system; P. Sing Babu, A. Goswami, V. S. Pandit; Nucl. Instr. and Meth. A 642 (2011)1. [6] Envelope equations for cylindrically symmetric space charge dominated multi species beam P. Sing Babu, A. Goswami, V. S. Pandit; Physics of Plasmas 18, 103117 ( 2011). [7] Effect of nonuniform radial density distribution on space charge dominated beam bunching P. Sing Babu, A. Goswami, V. S. Pandit; Physics of Plasmas 18, 103104 (2011). UFCYC-2012 A. Goswami 33

Publications (in 2012) [8] Transfer matrix of a Glaser magnet to study the dynamics of non-axisymmetric beam !! ! n A. Goswami, P. Sing Babu, V. S. Pandit , Nucl. Instr. and Meth. A 678 (2012) 14. [9] Investigation on beam envelope oscillations and amplitude growth in a high current compact cyclotron, A. Goswami, P. S. Babu , V. S. Pandit; Eur. Phys. J. Plus 127 (2012) 47. o i t n e t at [10] Beam focusing characteristic of an elliptical solenoid magnet in the presence of space charge, A. Goswami, P. Sing Babu, V. S. Pandit; Nucl. Instr. and Meth. A 685 (2012) 46. ___________________________ [11] Optimisation of beam line parameters for space charge dominated multi species beam using random search method, P. S. Babu, A. Goswami, V. S. Pandit, Phy. Lett. A (revision) y r r u o d n ki [12] Space charge dominated beam dynamics in a spiral inflector for a compact cyclotron, A. Goswami, P. Sing Babu , V. S. Pandit; Eur. Phys. J. Plus (revision) o f s k n [13] Transport characteristics of a Glaser magnet for non-axisymmetric space charge dominated beam, A. Goswami, P. S. Babu, V. S. Pandit; Physics of Plasmas (submitted) a h [14] A Vlasov Equilibrium for Space Charge Dominated Beam in a Misaligned Solenoidal Channel; P. Sing Babu, A. Goswami, V. S. Pandit, App. Phys. Lett. (submitted) T [15] Self-consistent space charge dominated beam dynamics in a spiral inflector, A. Goswami, P. Sing Babu , V. S. Pandit; Nucl. Instr. and Meth. A (submitted) UFCYC-2012 A. Goswami 34