Creation and Implementation of Computational Tools for Modeling and Optimizing Electrostatic Quadrupole (ESQ) Array Geometry in Support of Developing a Cost Effective and Compact RF Linear Accelerator*

Ion beams are widely used for discovery science and in industrial applications. At LBNL we are developing a compact multi-beam RF linear accelerator constructed using printed circuit board (PCB) wafers. Recent experiment has shown that a beam of Argon ions (Ar+) can be accelerated from 7 keV to 110 keV producing a 0.5 mA beam using 120 beamlets. To scale up to greater energies and currents a suite of computational tools are being developed to guide construction. These tools are created using Python in combination with a particle-in-cell (PIC) code Warp that is Python compatible. Here I will discuss the development and implementation of the computational tools to optimize the geometry for electrostatic quadrupoles (ESQ) arrays along with efficient simulations for delivering higher energy and current beams on target. 

Here I will discuss the development and implementation of computational tools to optimize the geometry for electrostatic quadrupole (ESQ) arrays. For an ESQ consisting of cylindrical rods of length L_q = 0.695 mm and clear bore aperture radius r_p =  0.55 mm we found that a rod radius of R = 1.304r_p minimizes the leading order error term in the multipole field expansion. We also found that rod curvature and L_q were the main contributors to field errors.