Radiation Transport

Platform Purpose

The NIF radiation transport platform provides a major new capability for experimental study of fundamental radiation hydrodynamics. The energy and precision of the NIF laser coupled with the NIF diagnostic suite will allow the study of radiatively driven phenomena in regimes previously inaccessible, allowing important advances in astrophysics, inertial fusion, radiation hydrodynamics, and related areas. Examples of experiments currently under study for this platform include ionization of molecular clouds, protostar formation in interstellar clouds, and radiation transport through inhomogeneous materials and density perturbations. These experiments will be enabled by NIF´s capability to measure radiation burnthrough, radiography of hydrodynamic features, and radiation transport via calorimetry, among other quantities.

The radiation transport platform was commissioned in FY2009.

Laser and Target Configuration

Figure 1 shows a typical radiation transport target (left) and overall experimental configuration (right).

Figure 1: (Left): Schematic of radiation transport platform showing half-hohlraum and driven target opposite the laser entrance hole (LEH) Right: Experimental configuration.

The target consists of half a gold hohlraum ("halfraum") 3.65 mm long and 5 mm in diameter with a 4-mm-diameter laser entrance hole (LEH). The sample to be tested is placed opposite to the LEH. Initial experiments to characterize the drive were carried out with a 200-µm-thick Ta₂O₅ aerogel foam. The halfraum is driven by 80 beams in the lower hemisphere of the NIF chamber with a total energy in the 150-200kJ range.

The combination of the halfraum shown in Fig. 1 and the laser pulse produce a relatively constant radiation drive exeeding 150 eV that lasts for approximately 7 nsec. Potential users should consider packages of interest that may be driven using this radiation source. Contact the NIF User Office for additional information.

Diagnostics

Standard diagnostics for this platform and their location (elevation, azimuth) are provided below. See the chamber geometry and diagnostic write-ups for additional information. For this platform, the primary diagnostics are Dante-1 (lower), used to measure the halfraum x-ray drive, and Dante-2 (upper) used to measure the x-ray flux through the sample. A gated or streaked x-ray detector may be mounted in the polar Diagnostic Instrument Manipulator (DIM) to record backlit images of the sample. Placement of a gold calorimeter above the sample package to integrate the x-ray energy that has passed through the target may also be feasible.

Diagnostic	Location
Dante-1	Fixed (143-274)
Dante-2	Fixed (64-350)
SXD/GXD	Polar DIM (0-0)

For further information:
Dr. Christopher J. Keane, LLNL
PHONE: (925) 422-2179
E-MAIL: Contact us