Optimizing Beam Transport in Rapidly Compressing Beams on the Neutralized Drift Compression Experiment - II

TL;DR

This paper presents a method to reconstruct beam envelope parameters from scintillator images to optimize beam transport in the NDCX-II accelerator, improving control of intense ion pulses for extreme matter heating.

Contribution

It introduces a technique to determine beam envelope parameters from imaging data, aiding in the optimization of beam transport in a plasma-filled drift section.

Findings

Reconstructed beam envelope parameters from scintillator images.

Optimized solenoid settings for improved beam trajectory.

Enhanced control of ion beam compression in NDCX-II.

Abstract

The Neutralized Drift Compression Experiment-II (NDCX-II) is an induction linac that generates intense pulses of 1.2 MeV helium ions for heating matter to extreme conditions. Here, we present recent results on optimizing beam transport. The NDCX-II beamline includes a 1-meter-long drift section downstream of the last transport solenoid, which is filled with charge-neutralizing plasma that enables rapid longitudinal compression of an intense ion beam against space-charge forces. The transport section on NDCX-II consists of 28 solenoids. Finding optimal field settings for a group of solenoids requires knowledge of the envelope parameters of the beam. Imaging the beam on scintillator gives the radius of the beam, but the envelope angle dr/dz is not measured directly. We demonstrate how the parameters of the beam envelope (r, dr/dz, and emittance) can be reconstructed from a series of images taken at varying B-field strengths of a solenoid upstream of the scintillator. We use this technique to evaluate emittance at several points in the NDCX-II beamline and for optimizing the trajectory of the beam at the entry of the plasma-filled drift section.