Optical fiducials for x-ray streak cameras at LLE

Abstract

The incorporation of an optical timing fiducial onto a time-resolved x-ray streak record permits one to precisely relate the x-ray emission to the incident laser pulse. At the Laboratory for Laser Energetics, our approach to recording fiducials is twofold. In addition to recording the x-ray emission on a bifurcated photocathode, we also streak the incident laser light at 351 nm, which is scattered from the target and an independent signal at 4ω0 (264 nm), which is derived by frequency quadrupling a tiny fraction of the OMEGA laser driver output. The signal at 4ω0 is transported through the vacuum wall to the streak camera photocathode via fiber optics. A 200-Å aluminum layer on mica is utilized for the UV sensitive photocathode. We will present examples and further details of this system.

(Sub)-Picosecond Spectral Evolution of Fluorescence Studied with a Synchroscan Streak-Camera System and Target Analysis

“…Often individual datasets contain internal tell-tales for absolute timing and of drift, e.g., Rayleigh or Raman scattering signals of the excitation pulse can be used to pin down the exact timing of the dataset. A fool-proof method for eliminating all sources of electronic drifts and jitter consists of directly illuminating a spot of the photocathode with the excitation pulse so as to obtain a fi ducial, which is an absolute timing reference (Jaanimagi et al, 1986;Uhring et al, 2003). Using drift compensation electronics, up to 1000 seconds of accumulation on the CCD chip can be performed without signifi cant deterioration of the temporal resolution.…”

X-ray streak camera cathode development and timing accuracy of the 4ω ultraviolet fiducial system at the National Ignition Facility

“…We would like to thank National Security Technologies and the Jupiter Laser Facility Fabrication Lab for providing the cathode samples used in this work. We would also like to note similar work done by Jaanimagi et al 10 …”

Capsule implosion optimization during the indirect-drive National Ignition Campaign

“…By contrast, the accuracy in defining the time between the first shock break-out and successive shock overtake will be a small fraction of the 30 ps temporal resolution, typically 10 ps, hence %0.2% over the 4.5 ns first shock transit time in the liquid D 2 . The contribution from the residual uncertainty in the calibration of the sweep speed using an in situ optical comb fiducial 91 is expected to be 1% for both shock velocities and coalescence depths, as long as any non-reproducible sweep speed non-linearities occur over periods longer than the 330 ps fiducial comb spacing.…”