Demonstration of controlled hydrogen fuel filling of a cryogenic NIF ignition target using a self-contained low pressure reservoir
Abstract
Ignition targets for the National Ignition Facility (NIF) require filling the fuel capsule with hydrogen. In this paper we describe a method for in-situ capsule filling using a low pressure reservoir (< 100 psi) which permits room temperature handling and transport. The ignition target consists of a capsule mounted in the center of a gold can called a hohlraum. A 4 micron ID fill tube is attached to the capsule and gradually expands to a 40 micron ID tube outside of the hohlraum. The tube then attaches to a 1 cc reservoir filled with 2 bars of D2. The temperature of the fill reservoir can be independently controlled. In operation the capsule is chilled to a temperature slightly above the triple point of D2 ( ∼ 20 K). The reservoir temperature is then increased (in the range of 50 - 120 K) so that the D2 vapor pressure in the fill reservoir exceeds the vapor pressure of D2 liquid at the temperature of the capsule. Under these conditions liquid D2 will condense in the capsule until the vapor pressure of the liquid in the capsule equilibrates with the reservoir pressure. Thus, the D2 fill can be controlled by setting the temperature of the fill reservoir. We have experimentally demonstrated the controlled fuel filling to better than 1% accuracy.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 2004
- Bibcode:
- 2004APS..DPPEM2006S