This PDF file contains the front matter associated with SPIE Proceedings Volume 8505, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.

We present the desired performance specifications for an advanced optical imager, which borrows practical concepts in high-speed microchannel plate (MCP) intensified x-ray stripline imagers and time-dilation techniques. With a four-fold speed improvement in state-of-the-art high-voltage impulse drivers, and novel atomic-layer deposition MCPs, we tender a design capable of 5 ps optical gating without the use of magnetic field confinement of the photoelectrons. We analyze the electron dispersion effects in the MCP and their implications for gating pulses shorter than the MCP transit time. We present a wideband design printed-circuit version of the Series Transmission Line Transformer (STLT) that makes use of 50-ohm coaxial 1.0 mm (110 GHz) and 1.85 mm (65 GHz) hermetically sealed vacuum feedthroughs and low-dispersion Teflon/Kapton circuit materials without the use of any vias. The STLT matches impedance at all interfaces with a 16:1 impedance (4:1 voltage) reduction, and delivers a dispersion-limited sharp impulse to the MCP strip. A comparison of microstrip design calculations is given, showing variances between method of moments, empirical codes, and finite element methods for broad, low-impedance traces. Prototype performance measurements are forthcoming.

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.*

We present a new diagnostic for the National Ignition Facility (NIF) [1,2]. The Streaked Polar Instrumentation for Diagnosing Energetic Radiation (SPIDER) is an x-ray streak camera for use on almost-igniting targets, up to ~10¹⁷ neutrons per shot. It measures the x-ray burn history for ignition campaigns with the following requirements: X-Ray Energy 8-30keV, Temporal Resolution 10ps, Absolute Timing Resolution 30ps, Neutron Yield: 10¹⁴ to 10¹⁷. The features of the design are a heavily shielded instrument enclosure outside the target chamber, remote location of the neutron and EMP sensitive components, a precise laser pulse comb fiducial timing system and fast streaking electronics. SPIDER has been characterized for sweep linearity, dynamic range, temporal and spatial resolution. Preliminary DT implosion data shows the functionality of the instrument and provides an illustration of the method of burn history extraction.

The National Ignition Facility South Pole Bang Time diagnostic uses polycrystalline diamond photoconductive detectors to measure x-ray bang time on capsule implosion shots. The original Laboratory for Laser Energetics PCD design was redesigned to eliminate ringing near the peak of the impulse response, and provide 30 picosecond resolution. The detector design, performance and x-ray laser impulse response tests used to characterize the detector are presented.

We present performance characterization measurements for Mach-Zehnder optical modulators to be fielded on NIF as a signal path upgrade for various diagnostics. Two different operating configurations will be explored including in phase quadrature and 90deg I/Q operation. Impulse response functions of x-ray emissions were conducted using the COMET laser facility at the Lawrence Livermore National Laboratory. Results from these short pulse laser driven plasma experiments are given along with comparisons to other recording instrumentation

The calibration of X-ray diagnostics is of paramount importance to the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). National Security Technologies LLC (NSTec) fills this need by providing a wide variety of calibration and diagnostic development services in support of the ongoing research efforts at NIF. The Xray source in the High Energy X-ray lab utilizes induced fluorescence in a variety of metal foils to produce a beam of characteristic X-rays ranging from 8 to 111 keV. Presented are the methods used for calibrating a High Purity Germanium detector, using NIST traceable radioactive sources, and compared against a silicon photodiode calibrated at Physikalisch Technische Bundesanstalt (PTB). A limited presentation of results from the recent calibration of the upgraded Filter Fluorescer X-ray Spectrometer is included.

The National Ignition Facility (NIF) is a 192-beam high energy laser designed for Inertial Confinement Fusion (ICF), and High Energy Density (HED) and basic science experiments. In order to achieve ignition with an ICF target, the beam and target alignment must be performed within very tight specifications. At the same time, in order to be able to conduct the wide range of HED and basic science experiments, the facility must be able to meet the tight tolerances for both main and offset backlighter beams and targets. To diagnose the ignition event, many different target diagnostics are employed, including optical, x-ray, and nuclear diagnostics. These target diagnostics must also be positioned accurately and reliably within very tight specifications in order to ensure good data is acquired. In this paper, we describe the strategy for beam, target, and diagnostic alignment at NIF.

The National Ignition Facility (NIF) fields multiple varieties of x-ray imaging systems used to diagnose the implosion physics of laser-driven fusion targets. The imagers consist of time-resolved x-ray detectors coupled with a snout assembly for spatial and/or spectral imaging. The instrument is mounted onto a cart that extends into the NIF target chamber, placing it in close proximity to the target and aligning with a tight tolerance using the Opposed Port Alignment System (OPAS). The OPAS is a modified, commercial Schmidt-Cassegrain optical telescope mounted at the target chamber port, opposite the Diagnostic Instrument Manipulator (DIM). In this paper, the approach used to characterize and align the x-ray imaging instruments is described. The characterization includes offline measurements of the pinhole assembly and the detector housing. Online, deviations of the DIM, as it is inserted along rails toward the target chamber center, are characterized and related to the OPAS view. An overview of the offline measurement stations is provided along with the process to develop the relationship between the offline alignment scopes and the OPAS as a function of DIM insertion. The combination of these measurements is used to mathematically construct the predicted location of the x-ray imager line of sight in the OPAS image space and determine the desired pinhole location to record data on a fusion experiment. The alignment accuracy of this approach will be discussed, as demonstrated with various x-ray instruments and pinhole configurations.

The requirements for beam and target alignment for successful ignition experiments on the National Ignition Facility (NIF) are stringent: the average of beams to the target must be within 25 μm. Beam and target alignment are achieved with the Target Alignment Sensor (TAS). The TAS is a precision optical device that is inserted into target chamber center to facilitate both beam and target alignment. It incorporates two camera views (upper/lower and side) mounted on each of two stage assemblies (jaws) to view and align the target. It also incorporates a large mirror on each of the two assemblies to reflect the alignment beams onto the upper/lower cameras for beam alignment. The TAS is located in the chamber using reference features by viewing it with two external telescope views. The two jaws are adjusted in elevation to match the desired beam and target alignment locations. For some shot setups, a sequence of TAS positions is required to achieve the full setup and alignment. In this paper we describe the TAS, the characterization of the TAS coordinates for beam and target alignment, and summarize pointing shots that demonstrate the accuracy of beam-target alignment.

Vendor supplied CMOS sensors were exposed to 14 MeV neutrons on yield shots in NIF and examined for damage. The sensors were exposed to multiple shots with a maximum fluence on one of the sensors of 4.3E11 n/cm². The results of post-shot testing will be presented. LLNL is investigating the suitability of CMOS imaging sensors for use in the camera of the ARIANE diagnostic which will mitigate the effects of the NIF neutron environment by dumping photoelectrons during the neutron pulse and then recording an image stored on a long persistence phosphor.

The National Ignition Facility requires a radiation-hardened, megapixel CMOS imaging sensor-based camera to be a direct physical and operational replacement for the CCD cameras currently used in x-ray streak cameras and gated imaging detectors. The first phase is a radiation-tolerant camera for characterization of radiation effects on the imaging sensor. This will be followed by a fully hardened version. The radiation-tolerant camera, based on the 2k by 2k CMV4000 sensor from CMOSIS Inc., has been built and optical performance was measured. Camera parts were selected to operate up to 10 krad(Si) and the camera incorporates a fast charge and dump of the sensor pixels, followed by image readout. This allows the dumping of charge due to the prompt radiation noise and then readout of the longer persistence phosphor signal from the x-ray diagnostics.

We describe the performance of a 512x512 gated CMOS read out integrated circuit (ROIC) with a 250 ps exposure time. A low-skew, H-tree trigger distribution system is used to locally generate individual pixel gates in each 8x8 neighborhood of the ROIC. The temporal width of the gate is voltage controlled and user selectable via a precision potentiometer. The gating implementation was first validated in optical tests of a 64x64 pixel prototype ROIC developed as a proof-of-concept during the early phases of the development program. The layout of the H-Tree addresses each quadrant of the ROIC independently and admits operation of the ROIC in two modes. If “common mode” triggering is used, the camera provides a single 512x512 image. If independent triggers are used, the camera can provide up to four 256x256 images with a frame separation set by the trigger intervals. The ROIC design includes small (sub-pixel) optical photodiode structures to allow test and characterization of the ROIC using optical sources prior to bump bonding. Reported test results were obtained using short pulse, second harmonic Ti:Sapphire laser systems operating at λ~ 400 nm at sub-ps pulse widths.

The path to successful inertial confinement fusion (ICF) requires to observe and control the micro balloon deformations. This will be achieved using X-ray microscope among other diagnostics. A high resolution, high energy X-ray microscope involving state-of-the-art toroidal mirrors and multilayer coatings is described. Years of experiments and experience have led to a small-scale X-ray plasma imager that proves the feasibility of all the features required for a LMJ diagnostic: spatial resolution of 5μm, broad bandwidth, millimetric field of view (FOV). Using the feedback given by this diagnostic, a prototype for the Laser MegaJoule (LMJ) experiments has been designed. The experimental results of the first diagnostic and the concepts of the second are discussed.

DIXI (dilation x-ray imager) will be used to characterize ICF (inertial confinement fusion) implosions on the NIF. DIXI utilizes pulse-dilation technology¹ to achieve x-ray imaging with temporal gate times below 10 ps. Time resolved x-ray measurements were conducted using the COMET laser facility at the Lawrence Livermore National Laboratory. Here we focus on some of the challenges faced by the large aperture photo cathode of the instrument and report on how to maintain a at photo cathode as well as how the required spatial resolution of the instrument is achieved.

From a point of a signal-to-background ratio, phosphors are a key component of micro channel plate (MCP) based x-ray framing cameras. In an MCP based framing camera, x-ray signal is converted to electrons, gated, amplified, and converted back to optical signal on the phosphor. To operate x-ray framing cameras in a harsh neutron induced radiation background of the National Ignition Facility, cathodeluminescence efficiency of the phosphor is very important. To avoid MCP damage due to high voltage breakdown, we have been operating phosphors below 3kV (acceleration field < 6 kV/mm). The signal-to-background ratio the camera can be significantly improved by increasing the phosphor potential to 10kV. We measured conversion efficiencies of standard phosphors at electron energies of 0.5 ~10 keV and assessed achievable performance of them with using a numerical model.

Gated X-Ray imagers have been used on many ICF experiments around the world for time resolved imaging of the target implosions. ARIANE (Active Readout In A Neutron Environment) has been developed for use in the National Ignition Facility and has been deployed in multiple phases. Phase 1 (complete) known as ARIANE Ultra Light (Alignment proof of concept), Phase 2a known as ARIANE Light (complete) (X-ray gated detector with electronic recording), Phase 2b (complete) (X-ray gated detector with film recording) and Phase 3 known as ARIANE Heavy which is currently under development. The ARIANE diagnostic is comprised of the following subsystems: pinhole imaging system, filtering, detector head, detector head electronics, control electronics, CCD, and film recording systems. The phased approach allows incremental increases in tolerance to neutron yield. Phase 2a and 2b have been fielded successfully and captured gated implosion images on CCD and film at neutron yields up to 7 x 10¹⁴. As the yields in the NIF increase Phase 3 will be a longer term solution incorporating an indirect optical path, hardened advanced detectors and significant (tons) of shielding. Design and Initial commissioning data for Phase 1-2b are presented here.

Gated X-Ray Detectors (GXD) are considered the work-horse target diagnostic of the laser based inertial confinement fusion (ICF) program. Recently, Los Alamos National Laboratory (LANL) has constructed three new GXDs for the Orion laser facility at the Atomic Weapons Establishment (AWE) in the United Kingdom. What sets these three new instruments apart from what has previously been constructed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is: improvements in detector head microwave transmission lines, solid state embedded hard drive and updated control software, and lighter air box design and other incremental mechanical improvements. In this paper we will present the latest GXD design enhancements and sample calibration data taken on the Trident laser facility at Los Alamos National Laboratory using the newly constructed instruments.

Narrowband x-ray imagers using spherically bent crystals have been implemented on all three laser facilities (MTW, OMEGA EP, and OMEGA) at the University of Rochester’s Laboratory for Laser Energetics. These spherical crystal imagers (SCI’s) use a 150-μm-thick, 25.4-mm-diam quartz crystal cut either along the 2131 plane to reflect the Cu K_α line at ∼8 keV with a Bragg angle of 88.7^° or along the 1011 plane to reflect the Si He_α line at ∼1.865 keV with a Bragg angle of 83.9^°. The SCI systems can be set up to either image the self-emission of a laser-heated target or to backlight a high-energy-density plasma object.