CERN Accelerating science

Article
Title	Numerical Model of the DARHT Accelerating Cell
Author(s)	Hughes, Thomas P ; Davis, Harold ; Genoni, Thomas C ; Kang, Mike ; Prichard, Benjamin A
Affiliation	(ATK-MR, Albuquerque, New Mexico) ; (LANL, Los Alamos, New Mexico)
Publication	2005
In:	21st IEEE Particle Accelerator Conference, Knoxville, TN, USA, 16 - 20 May 2005, pp.2269
Subject category	Accelerators and Storage Rings
Abstract	The DARHT-2 facility at Los Alamos National Laboratory accelerates a 2 microsecond electron beam using a series of inductive accelerating cells. The cell inductance is provided by large Metglas cores, which are driven by a pulse-forming network. The original cell design was susceptible to electrical breakdown near the outer radius of the cores. We developed a numerical model for the magnetic properties of Metglas over the range of dB/dt (magnetization rate) relevant to DARHT. The model was implemented in a radially-resolved circuit code, and in the LSP* electromagnetic code. LSP simulations showed that the field stress distribution across the outer radius of the cores was highly nonuniform. This was subsequently confirmed in experiments at LBNL. The calculated temporal evolution of the electric field stress inside the cores approximately matches experimental measurements. The cells have been redesigned to greatly reduce the field stresses along the outer radius.