Implementation of spread mass model of ion hose instability in lamda

Abstract

The ion-hose instability sets limits on the allowable vacuum in the DARHT-2 linear induction accelerator (2kA, 18.6MeV, 2μs). Lamda is a transport code which advances the beam centroid and envelope in a linear induction accelerator from the injector to the final focus region. The code computes the effect of magnet misalignment, beam breakup instability, imagedisplacement instability, and gap voltage fluctuation. To support the experiments, we have implemented the SM model of ion-hose instability into Lamda. Unlike the ordinary SM ion-hose code which assumes the uniform axial magnetic field, Lamda ion-hose calculation includes varying axial magnetic field, accelerating beam, gas pressure file, varying beam radius, and elliptical beam. This paper describes the Lamda ion-hose instability code, the benchmarks against a semi-analytical SM code, and the particle-in-cell code Lsp. A prediction of ion-hose instability for a 2.5MeV-1.4kA beam in the DARHT-2 is also presented.

Novel correction method for X-ray beam energy fluctuation of high energy DR system with a linear detector

“…Obvious bright and dark streak artifacts in the DR image are, however, still detectable, as a result of the amplification of a subtle energy fluctuation of the Xray beam by the linear detector with a high dynamic range and high sensitivity used in the DR scanning systems. Related correction methods for the energy fluctuation of the X-ray beam mainly focus on upgrading the hardware and the accelerator structure design [9][10][11], which are either actually difficult to implement in a certain duration or raise the cost of the hardware significantly. In this study, we constructed a software-based method to correct the energy fluctuation of the X-ray beam.…”