San Diego, California, 17-19 June 2002

Calculations and Experiments of IFE Target Output and Chamber Response

Gregory A. Moses, Robert R. Peterson, Donald A. Haynes, Jr., Igor E. Golovkin, Jiankui Yuan, and Gregory Rochau

Fusion Technology Institute, University of Wisconsin-Madison,

1500 Engineering Drive, Madison, WI 53706

mosesengr.wisc.edu

Institute of Laser Engineering, Osaka University

The emission of photons and energetic ions by the burn and subsequent explosion of Inertial Fusion Energy (IFE) targets poses a threat to the survival of the target chambers in future IFE power plants. Immediately after the deposition of target output, the chamber can experience sufficient heating to cause vaporization, melting, and shock loading on chamber walls. Until high yield targets can be ignited in laboratory experiments, predictions of the nature of the target output and the response of the target chamber must be made with radiation-hydrodynamics computer codes that are validated with relevant smaller scale experiments. Physical models of equation of state, opacity and radiation transport are in special need of validation.

Recently, a new class of IFE direct-drive laser targets has been designed at the Naval Research Laboratory. These targets use a thin layer of high atomic number material on the outside edge of the target to generate thermal radiation that is absorbed in an ablator of plastic foam wetted with liquid DT. In the process the symmetry and stability of the implosion is improved. The use of these targets in dry-wall chambers is being studied with the BUCKY computer code. Experiments for validation of the code are being designed and performed. BUCKY calculates implosion and burn of the target as well as the x-ray and debris output during explosion and target expansion. The code also calculates the response of the chamber to the target output.

We will present calculations of x-ray and debris output from direct drive IFE targets and discuss how the output spectrum determines the chamber response. We will discuss the physics models used in these calculations. We will discuss the validation of BUCKY through experiments and the need for additional model development. On-going validation experiments on the Z and RHEPP facilities at Sandia National Laboratory will be discussed. In this work, scientists at Sandia, the Naval Research Laboratory, University of California-San Diego, and University of California-Berkeley are collaborators.