DARHT II Scaled Accelerator Tests on the ETA II Accelerator

Abstract

The DARHT II accelerator at LANL is preparing a series of preliminary tests at the reduced voltage of 7.8 MeV. The transport hardware between the end of the accelerator and the final target magnet was shipped to LLNL and installed on ETA II. Using the ETA II beam at 5.2 MeV we completed a set of experiments designed reduce start up time on the DARHT II experiments and run the equipment in a configuration adapted to the reduced energy. Results of the beam transport using a reduced energy beam, including the kicker and kicker pulser system will be presented.

Status of the DARHT 2nd Axis at Los Alamos National Laboratory

“…C s i t A 2nd to produce four pulses. Tests on LLNL's ETA-II have aceeao,kckradtre wil bgniMa207Al been conducted in support of these tests and are discussed aceeao'n ontemcopnnswl ei lc by J. T. Weir, et al [11], and Y-J Chen, et al [12] in anfulbmeeryndpfoacewlbesdi.…”

Particle Beam Radiography

“…After exiting the LIA, the long pulse is sliced into four shorter pulses by a fast kicker system in the downstream transport (DST), with the un-kicked beam diverted to an offline dump [122][123][124][125][126][127][128][129][130]. The durations of the kicked pulses are individually programmable, from 20 ns to >100 ns, and this feature is used to tune the individual doses to the dynamic experiment.…”

Scaled Accelerator Test For the DARHT-II Downstream Transport System

“…Many of the issues discussed earlier have been studied on the 5-MeV, 2-kA, 60-ns (with 40-ns flattop for δγ⁄γ = ± 1%) Experimental Test Accelerator II (ETA-II) [5], [6], [7], [8], [9] as shown by the check marks in Table 1. However, ETA-II is a single short pulse machine and cannot address issues specially concerning long pulse and multiple pulses.…”

“…Instead of waiting to learn about these physics concerns after completion of all the accelerator cells, we will test them on a scaled DARHT-II accelerator with a lower energy and current since most of these physics issues scale with I/γβ. The DARHT-II transport hardware has recently been tested on ETA-II [9]. To take the advantage of the tuning experience gained from the ETA-II's DARHT-II transport experiment, the scaled DARHT-II accelerator's beam parameters, 7.8-MeV and 660-A, are chosen to be close to the ETA-II DARHT-II transport experiment's parameters while I/γβ is kept about the same value as that for the full energy machine.…”

“…Finally, the x-ray spot sizes for all pulses need to meet radiography requirement even though the high energy intensity beam pulses would interact with the time-evolving target plasma. Many of these issues had been studied on the 5-MeV, 2-kA, 60-ns Experimental Test Accelerator II (ETA-II) [5], [6], [7], [8], [9]. However, ETA-II is a single pulse machine and cannot address long pulse and multiple pulse issues.…”