Photoinjector optimization using a derivative-free, model-based trust-region algorithm for the Argonne Wakefield Accelerator

8th International Particle Accelerator Conference

Neveu, N.^1,2 ; Larson, J.^1 ; Power, J.G.^1 ; Spentzouris, L.^2

Argonne National Laboratory, Lemont

IL, United States^1

Illinois Institute of Technology, Chicago

IL, United States^2

关键词: Accelerating cavities;    Derivative-free;    Model-based OPC;    Optimization algorithms;    Optimization parameter;    RF photoinjector;    Three parameters;    Trust region algorithms;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/874/1/012062/pdf
DOI  :  10.1088/1742-6596/874/1/012062

来源: IOP

【 摘 要 】

Model-based, derivative-free, trust-region algorithms are increasingly popular for optimizing computationally expensive numerical simulations. A strength of such methods is their efficient use of function evaluations. In this paper, we use one such algorithm to optimize the beam dynamics in two cases of interest at the Argonne Wakefield Accelerator (AWA) facility. First, we minimize the emittance of a 1 nC electron bunch produced by the AWA rf photocathode gun by adjusting three parameters: rf gun phase, solenoid strength, and laser radius. The algorithm converges to a set of parameters that yield an emittance of 1.08 μm. Second, we expand the number of optimization parameters to model the complete AWA rf photoinjector (the gun and six accelerating cavities) at 40 nC. The optimization algorithm is used in a Pareto study that compares the trade-off between emittance and bunch length for the AWA 70MeV photoinjector.