Streaked Radiography

Platform Purpose

The x-ray streaked radiography experiments planned by the Capsule Integrated Experimental Team (IET) are the first capsule radiography experiments in a series of sub-campaigns with the goal of tuning the ignition hohlraum and capsule design for ignition experiments in 2010. The experiments require 184 drive beams smoothed with continuous phase plates (CPPs), smoothing by spectral dispersion (SSD), and polarization smoothing (PS). In addition, they require 8 beams with smaller CPPs for creating the x-ray backlighter. Cryogenic hohlraums with empty capsules will be used.

These shots are to set the initial ablator mass and peak drive flux by measuring and controlling the ablator mass remaining and peak capsule implosion velocity. One-dimensional imaging streaked radiography will be used at ≈ 8 keV with a 2- to 3-ns-long area backlighter hit from the back side. The streak camera will provide 20-μm, 20-ps resolution and will be equipped with a 4ω fiducial train of eight 100-ps pulses spaced every 300 ps. It is expected that the mass remaining from an Abel inversion of the streaked radiograph will be measured to 10% accuracy and the peak implosion velocity to 2% accuracy.

Laser and Target Configuration

The laser and target configurations for this platform are summarized below:

Target	# beams	Laser energy/Pulse width
Au:B hohlraum, cryogenic, H-He gas fill	184	1-MJ, 16-nsec shaped pulse
Au:B-lined U hohlraum, cryogenic, H-He gas fill	184	1- to 1.2-MJ, 16-nsec shaped pulse
Cu BL foil	8	40 kJ, 2.5 ns

Hohlraums will be "Scale 1.07". Dimensions for this hohlraum are summarized below:

Target	Hohlraum Length	Hohlraum width	Laser Entrance Hole (LEH)
Scale 1.07	10.01 mm	5.44 mm	3.01 mm

The laser will employ Polarization Smooting and Smoothing by Spectral Dispersion, with a nominal bandwidth of 60 GHz for the latter. A 2-color wavelength detuning, typically 0.5Å between inner and outer cones will also be required. Additional detailed modifications to the laser and target will be made to suit the needs of particular experiments; please see below if you wish further information.

A generic experimental configuration is shown below:

Diagnostic Configuration

Standard diagnostics for this platform and their location (elevation, azimuth) are provided below. See Chamber Geometry and Diagnostics for additional information.

Diagnostic	Location
SXDB- HXRI	DIM 90-315
Dante-1	Fixed (143-274)
FABS/NBI	Q31B, Q36B
FFLEX	Fixed (90-110)
SXI, Top/Bottom	Fixed ([18-123],[161-326])

For further information on scientific opportunities at the NIF, please contact:
Dr. Christopher J. Keane, LLNL
PHONE: (925) 422-2179
E-MAIL: Contact us