A compact UV timing fiducial system for use with x-ray streak cameras at NIF

Abstract

We present the design of a compact UV (263-nm) timing fiducial system for use with x-ray streak cameras at the National Ignition Facility (NIF). The design consists of remote fiber amplification of an infrared 1053-nm (1ω) seed, a free-space optical path that has two stages of frequency conversion from 1ω to the fourth harmonic (4ω), and fiber delivery of the 4ω signal via output fiber for use with an x-ray streak camera. This is all contained within an airbox that can reside in a vacuum. The 1ω seed and the pump light for the fiber amplifier is delivered to the airbox via optical fiber (∼100 meters) from a location in the NIF that is shielded from neutron radiation generated from imploding targets during system shots. When complete, the system will be able to provide timing fiducials to multiple x-ray streak cameras on the same system shot. We will present data that demonstrates end-to-end system performance. *

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

“…The energy of the 4ω fiducial pulses was measured at the DISC input fiber with a Coherent pyroelectric energy detector. 4 Four photocathode materials were evaluated for sensitivity to the 4ω fiducial: Aluminum, gold, silver, and titanium. The Al, Ag, and Ti metals were evaporation deposited onto fused silica substrates to a thickness of 1000 Å.…”

High performance imaging streak camera for the National Ignition Facility

“…The resulting train of six 4ω pulses, each with 45 ps pulse duration and ∼300 ps pulse separation, is isolated from the other frequencies with a dichroic mirror and is launched into a large-core fiber for delivery to the photocathode in reflection geometry. 9 A final addition to the diagnostic was a split photocathode that was developed in order to measure both the NIF x-ray signal and UV fiducial pulses. 10 A sample streaked radiograph of an imploding convergent ablator fuel capsule, along with the 4ω fiducial pulse train is shown in Figure 3.…”

Measuring x-ray burn history with the Streaked Polar Instrumentation for Diagnosing Energetic Radiation (SPIDER) at the National Ignition Facility (NIF)

“…The pulse comb appears as a series of six spots on the left edge of the image that spans 1.5ns. The pulses are produced by siphoning a small percentage of the NIF seed laser, then splitting the pulse with a fiber optic splitter, then temporally delaying each pulse by sending the pulse through different length fiber optic cables [6,9]. The pulses are frequency quadrupled to 263 nm using two second harmonic crystals.…”