Emittance growth of kicked and mismatched beams due to amplitude-dependent tune shift

Emittance growth in the DARHT Axis-II Downstream Transport

Using a particle-in-cell (PIC) code, we investigated the possibilities for emittance growth through the quadrupole magnets of the system used to transport the high-current electron beam from an induction accelerator to the bremsstrahlung converter target used for flash radiography. We found that even highly mismatched beams exhibited little emittance growth (< 6%), which we attribute to softening of their initial hard edge current distributions. We also used this PIC code to evaluate the accuracy of emittance measurements using a solenoid focal scan following the quadrupole magnets. If the bea…

Modeling Transverse Space Charge effects in IOTA with pyORBIT

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 symple…

E302效率-不稳定性实验在FACET-II设施中的初步结果

First results from the E302 efficiency$\unicode{x2013}$instability experiment at the FACET-II facility

本文报告了FACET-II设施E302实验中首次观测到等离子体加速器束破裂不稳定性现象，通过特定光学设置和新型诊断方法分析横向不稳定性，并结合3D粒子-网格模拟验证结果。