Apparatus for verification of beta heating driven layer uniformity in solid deuterium–tritium

Abstract

A solid deuterium–tritium fuel layer within a spherical inertial confinement fusion target will be driven uniform by β-decay energy if the target is held in an isothermal environment. The apparatus we constructed to verify this process provides an isothermal and radiation-tight environment. Heat exchange between the target (≂20 K) and the environment (4.2 K) is regulated by controlling the helium exchange gas through a specially constructed manifold. A unique optical system maintained at low temperatures allows direct observation of the fuel layer uniformity. Tritium containment in the event of a target failure is assured by tungsten–inert gas welding of the stainless-steel structure. This system conveniently fits a standard vendor supplied 100-l Dewar, and is designed to minimize boiloff and cooldown losses by means of an efficient helium vapor counterflow system. We have also incorporated a vibration isolation system to permit holographic interferometry imaging and evaluation of the fuel layers.

The infrared-induced temperature distributions of solid D2ices

“…To achieve ignition and burn in inertial-confinementfusion (ICF) experiments, [1][2][3][4][5][6][7] one critical challenge is to form a very smooth (roughness less than 1 µm) and uniform deuterium-tritium (D-T) ice layer covering the internal surface of a spherical capsule. The natural heating from the β decay of tritium can redistribute the solid D-T ice towards a smooth layer, but such a layer is typically a multicrystalline surface and not perfectly smooth.…”