Magnetic field of DECY-13 from numerical extrapolation of the measurement result for beam trajectory simulations in central region

Abstract

DECY-13 cyclotron is a radioisotope production cyclotron developed by PSTA. In a cyclotron, it is important to understand magnetic fields and electric field distribution for the proton beam trajectories. This paper describes the distribution of the magnetic field from the experimental measurement. Magnetic field has been converted into 3-dimensional data by extrapolation. Data validation was done by comparing the Opera3D simulation and used in simulations of the beam trajectories. Simulations were carried out by using Scilab 5.4.1 and the Runge-Kutta (RK4) approximation method. The parameters used in DECY-13 cyclotron were 40 kV Dee voltage with a radiofrequency (RF) 77.66 MHz and a fourth-harmonics type. The calculations and simulations result showed the beam could pass through the puller at the distance of the ion source with a puller was 6 mm and the optimum distance of 4 mm. The largest difference in error at z = 6 mm was 0.023 T of the average magnetic field 1.275 T. The phase acceptance in horizontal and vertical motion in the central region was about 38 Degrees from -19° to 19°. This experimental and simulation data could be used as a reference for DeCY-13 cyclotron magnetic and electric field distribution profiles.

Evaluation of shimmed DECY-13 MeV Cyclotron Magnet Using H- Beam Tracking Simulation

“…Both are using the designed electric field distribution as computed using OPERA3D TM and Tosca module. Both beam tracking reached energy of 13 MeV, having similar isochronous line, and vertical deviation of the beam less than 6 mm [8]. Fig.…”

“…4. For extrapolation up to z = 6, the maximum difference from the designed value is about 0.02 T [8,10]. Fig.…”

“…In addition, for each increase towards z, three finite difference approaches were used to find the values of B z , B x , and B y namely (1) central difference in the middle of the data, (2) forward difference and backward difference in the edge of the edge data, and (3) a mixture of forward difference or backward difference with the central difference in the middle edge data, as shown in Fig. 2 [8,10]. it is devided into 4 quadrants, namely V1, V2, V3, and V4, and the size of binary data is about 56 MB for each quadrant.…”

“…To check the accuracy of the magnetic field interpolation and extrapolation, the designed magnetic field distribution (B z ) as computed by using OPERA3D TM and Tosca module was taken at 5 mm step in 2 dimension (x,y) at z = 0, fed to equations (6)- (8), and the result was compared to the original designed data. The comparison are shown in Figs.…”

“…Figures 6(a)-(d) [8] show some results of the interpolation and extrapolation to the measured magnetic fields. The differences between the measured and the designed magnetic fields can be clearly seen.…”