San Diego, California, 17-19 June 2002

Ionized Flibe Vapor Condensation Rate on a Simulated Flibe Liquid Chamber: Experimental and Numerical Investigation

A. Ying, M. Abdou, P. Calderoni, T. Sketchley, M. Ni

Department of Mechanics and Aerospace Engineering

University of California, Los Angles

Los Angeles, CA 90095

The idea of using a pulsed electrothermal plasma gun for simulating an IFE target explosion for rapid vapor generation and, subsequently, for the investigation of vapor clearing rates and condensation issues related to IFE liquid chambers appears feasible. As presented in reference 1, the energy can be deposited inside the gun within 100 ms (which is much shorter than the time required for the condensation process), while the trace coupons collected inside the chamber show evidence of flibe deposition. To safely increase the power delivered to the chamber and to produce a prototypical amount of flibe vapor in the HYLIFE-II reactor, the facility has been recently upgraded. This paper reports on recently obtained experimental and modeling results, which are aimed at understanding, predicting and providing data of vapor clearing and condensation rates for feasibility assessment and code evaluation. Numerically, a 1-D condensation module is constructed and coupled into the numerical code Tsunami, which is capable of evaluating the temporal evolution of the hydrodynamic parameters of the vapor cloud generated by the deposition of the fusion heat on liquid surfaces. This 2-D hydrodynamic code is structured to accept mass transfer conditions at the boundaries. The positive (evaporation) or negative (condensation) mass flux is evaluated by the condensation module. The code is applied to the geometry and conditions encountered in the constructed condensation chamber that is attached to the plasma source. In this first series of experimental efforts, the main chamber wall is uniformly heated, and its temperature progressively increased up to 600 ^oC to study the temperature effect on flibe condensation. To induce the discharge, the chamber is filled with low-pressure flibe vapors from an independently heated in-situ inventory. Since the plasma gun can not be significantly heated, traces of argon are injected if needed, and the effect of the presence of non-condensable gas on condensation rates analyzed. The pressure in the chamber is measured with a piezoresistive transducer. In addition, a series of fast response instruments that couple capacitance manometers and a pirani sensor are mounted on an independently heated tube to keep their temperatures in the operating regime. The tube acts as a cold trap and its effect on the condensation enhancement is taken into account. Trace coupons are inserted in the chamber at different locations for post analysis. Auger analysis is performed to trace the distribution of different Li components through the chamber.

Reference

1. Calderoni, P., Ying, A., Sketchley, T., Abdou, M., "Description of a Facility for Vapor Clearing Rate Studies of IFE Reactors Flibe Liquid Chambers", Fusion Technology, vol. 39(n2), pp.711-715, March 2001