160. PLASMA FORMATION AND CORONAL EVOLUTION IN HIGH CURRENT, PULSE POWER EXPERIMENTS

Department: Mechanical & Aerospace Engineering
Research Institute Affiliation: Center for Energy Research (CER)
Faculty Advisor(s): Farhat Beg

Primary Student
Name: David Michael Haas
Email: dmhaas@ucsd.edu
Phone: 858-822-2176
Grad Year: 2008

Student Collaborators
Robert E. Madden, rmadden@ucsd.edu | Yossof Eshaq, eshaq007@yahoo.com | Utako Ueda, utakoueda@gmail.com | Gilbert Collins, gilbert@ucsd.edu

Abstract
The path to Inertial Confinement Fusion (ICF) is rapidly accelerating. Advancements in insulating materials and high current switches as well as low inductance designs have enabled us to probe new High Energy Density Physics regimes. In order to further ICF it is necessary to develop a bright source of hard x-rays. Currently, arrays consisting of 200 metallic wires, heated with 20 mega Amps are used to explore how plasma behaves under extreme conditions. However, in order to produce fusion, a current of 60 MA is needed. Before proceeding it is imperative that we develop laws governing the scaling of the plasma to higher currents. Presently, we are able to capture the plasma dynamics through the use of complex diagnostics. However a thorough description and a high level of confidence in the initiation, ablation, and formation of the plasma, regarding scaling to ICF current levels, is still lacking. In addition to being a resource for High Energy Density Physics research, the x-pinch also is a small and bright x-ray emitter. This makes the x-pinch an ideal diagnostic tool (backlighting) for ICF experiments. The results presented here are from experiments studying the mass ablation, propagation, and jet development exhibited in pulsed power experiments. All results were obtained on a compact pulsar having a maximum current of 80 kA with a rise-time of 50ns. Optical probing diagnostics included side on interferometry, shadowgraphy, and schlieren imaging. Time gated x-ray images were recorded simultaneously to trace the emission profile. Several wire materials, including aluminum, tungsten, and stainless steel, were investigated to determine the effect of radiation cooling. Plasma jets were formed from x-pinches and low wire number conical wire arrays. They were observed to form between the electrodes and propagating above the anode. Jet parameters such as velocity, density, and temperature were investigated, along with dimensionless parameters to assess scalability to astrophysical regimes.

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