Modeling Transverse Space Charge effects in IOTA with pyORBIT

TL;DR

This paper models transverse space charge effects in IOTA using pyORBIT, benchmarking results, exploring steady state initialization, and comparing simulations with theoretical predictions to understand nonlinear integrability impacts.

Contribution

It introduces a comprehensive modeling approach for space charge effects in IOTA, including benchmarking, steady state techniques, and validation against theory.

Findings

Benchmarking confirms pyORBIT accuracy against MADX.

Steady state initialization reduces emittance growth.

Simulated tune shifts agree with theoretical predictions.

Abstract

The role and mitigation of space charge effects are important aspects of the beam physics research to be performed at the Integrable Optics Test Accelerator (IOTA) at Fermilab. The impact of nonlinear integrability (partial and complete) on space charge driven incoherent and coherent resonances will be a new feature of this accelerator and has the potential to influence the design of future low energy proton synchrotrons. In this report we model transverse space charge effects using the PIC code pyORBIT. First we benchmark the single particle tracking results against MADX with checks on symplecticity, tune footprints, and dynamic aperture in a partially integrable lattice realized with a special octupole string insert. Our space charge calculations begin with an examination of the 4D symplecticity. Short term tracking is done first with the initial bare lattice and then with a matching of the rms values with space charge. Next, we explore slow initialization of charge as a technique to establish steady state and reduce emittance growth and beam loss following injection into a mismatched lattice. We establish values of space charge simulation parameters so as to ensure numerical convergence. Finally, we compare the simulated space charge induced tune shifts and footprints against theory.