CYCLOTRONS 2010 - List of Authors (Sarma, P.R.)

Paper	Title	Page
MOPCP079	Optimization of Sector Geometry of a Compact Cyclotron by Random Search Method	212
	P. Sing Babu, A. Goswami, V.S. Pandit, P.R. Sarma DAE/VECC, Calcutta, India
	A compact four sector 10 MeV, 5 mA proton cyclotron is being developed at VECC, Kolkata. Proton beam at 80keV from a 2.45 GHz ion source (under testing) will be first collimated and bunched and will be injected axially in the central region where a spiral inflector will place the beam on the orbit. This paper describes the procedure of optimizing the sector geometry of the magnet to obtain the desired isochronous field. Due to fringe field effect, analytical formulae do not predict the correct sector shape particularly at the lower radii in the cases of compact cyclotrons, where hill gap is very small and valley gap is large. Hence a 3D code becomes necessary to obtain the correct shape and size of the magnet sectors. This involves a lengthy iterative procedure of determining the hill angle at a large number of radii. In our procedure magnet sector is described in terms of a small number of parameters which are iteratively determined by random search technique geared to minimize the frequency error. 3D magnetic field data and results of equilibrium orbit code are used as input to the code developed for the optimization.

Paper

Title

Page

Optimization of Sector Geometry of a Compact Cyclotron by Random Search Method

212

P. Sing Babu, A. Goswami, V.S. Pandit, P.R. Sarma
DAE/VECC, Calcutta, India

A compact four sector 10 MeV, 5 mA proton cyclotron is being developed at VECC, Kolkata. Proton beam at 80keV from a 2.45 GHz ion source (under testing) will be first collimated and bunched and will be injected axially in the central region where a spiral inflector will place the beam on the orbit. This paper describes the procedure of optimizing the sector geometry of the magnet to obtain the desired isochronous field. Due to fringe field effect, analytical formulae do not predict the correct sector shape particularly at the lower radii in the cases of compact cyclotrons, where hill gap is very small and valley gap is large. Hence a 3D code becomes necessary to obtain the correct shape and size of the magnet sectors. This involves a lengthy iterative procedure of determining the hill angle at a large number of radii. In our procedure magnet sector is described in terms of a small number of parameters which are iteratively determined by random search technique geared to minimize the frequency error. 3D magnetic field data and results of equilibrium orbit code are used as input to the code developed for the optimization.