Date: Thursday, Apr 10th
Presenter: David Donovan, Sandia National Laboratories
The international fusion research community is preparing to construct the largest fusion experiment to date, ITER, which will serve as a technological gateway to building a full-scale fusion power plant. Among the most critical fusion technology challenges to be addressed are plasma-surface interactions. The plasma facing components of a fusion energy system are exposed to extreme heat flux as well as plasma and radiation damage. Effective measurements of the exposure conditions of the walls and an understanding of the damage mechanisms to the material are essential to the design of a successful fusion power plant.
In this presentation, I will discuss our recent measurements collected from diagnostics within the DIII-D tokamak in San Diego, currently the largest operating magnetically confined fusion experiment in the country. This work led to a better understanding of the correlation between plasma and heat flux diagnostics than has previously been achieved. We have also undertaken laboratory-scale materials studies at Sandia California, where we have used atomic force and electron microscopy to characterize surface morphology changes to tungsten after helium ion exposure. These experiments replicate a key damage mechanism to the tungsten armor that will protect the surfaces exposed to the highest heat loads in a fusion power facility. I will conclude with a discussion of tritium permeation studies under development in cooperation with Idaho National Laboratory on the Tritium Plasma Experiment. An operating fusion power plant will require substantial inventories of tritium for fuel, making a thorough understanding of tritium retention and permeation crucial to properly assess risk of operation and disposal of components. This presentation will detail how these fusion technology challenges have been studied through a variety of experimental methods from small scale devices to large collaborative research facilities.
David Donovan is currently a post-doctoral research associate at Sandia National Laboratories/California in the Hydrogen and Metallurgy Sciences Department. He received his PhD in Nuclear Engineering from the University of Wisconsin-Madison in 2011, under the supervision of Professor Gerald Kulcinski of the Fusion Technology Institute. His PhD work was in the area of Inertial Electrostatic Confinement (IEC) Fusion for the purpose of creating and utilizing small-scale neutron generating devices to detect explosives and other illicit materials. His work at Sandia has been in the area of plasma-surface interactions in magnetically confined fusion devices. He has collaborated extensively with the DIII-D tokamak operated by General Atomics in San Diego, CA as well as with the Tritium Plasma Experiment located at Idaho National Laboratory. At Sandia, he has also developed expertise in grazing incidence x-ray diffraction and atomic force microscopy, and use of laboratory scale RF and microwave plasmas.