SARAF Simulations with 6D Waterbag and Gaussian Distributions

Beam dynamics calculations for the SARAF accelerator are presently being performed at Soreq as reported by S. Halfon and G. Feinberg[2] in these proceedings. This effort at Soreq allows us to better understand the design and possible limitations of the planned SARAF accelerator facility. We present results of the beam dynamics simulations performed at Soreq with the General Particle Tracer (GPT) simulation program[3]. This computer code enables precise calculations of particle tracking, taking into account realistic 3D fields of accelerating and focusing elements and also effects of space charge. GPT contains provisions for generating random particles, and includes a variety of possible distributions. It is becoming popular for simulating particles in RF accelerators to generate the particle distribution according to a 6D ellipsoid, with either a Waterbag or Gaussian distribution. The 6D ellipsoid establishes the particle correlations in x-x', y-y', and z-z', or ψ-ΔE spaces. The Waterbag option establishes a uniform distribution within the 6D ellipsoid, while the Gaussian option establishes a density profile with a Gaussian falloff. ACCEL GmbH[4], in addition to designing the SARAF LINAC, has performed extensive beam dynamics simulations assuming a 6D ellipsoid with a Waterbag distribution. GPT version 2.52 has no provisions for a 6D ellipsoid, but it does contain option for linking a user routine to the GPT code. We embarked on developing algorithms for creating a 6D ellipsoid, with a Waterbag or Gaussian distribution, and incorporating a reliable code into the GPT particle generator. This code was tested and checked for consistency and reliability