Articles you may be interested inSoft x-ray backlighting of cryogenic implosions using a narrowband crystal imaging system (invited)a) Rev. Sci. Instrum. 85, 11E501 (2014); 10.1063/1.4890215 High-energy, high-resolution x-ray imaging on the Trident short-pulse laser facilitya) Rev. Sci. Instrum. 79, 10E905 (2008); 10.1063/1.2965012High-brightness, high-spatial-resolution, 6.151 keV x-ray imaging of inertial confinement fusion capsule implosion and complex hydrodynamics experiments on Sandia's Z accelerator (invited) Rev. Sci. Hard x-ray imaging for measuring laser absorption spatial profiles on the National Ignition Facility Rev. Sci. Instrum. 77, 10E310 (2006); 10.1063/1.2216991 X-ray imaging of cryogenic deuterium-tritium layers in a beryllium shell

Fueling of a commercial Inertial Fusion Energy (IFE) power plant consists of supplying about 500,000 fusion targets each day. The most challenging type of target in this regard is for laserdriven, direct drive IFE. Spherical capsules with cryogenic DT fuel must be injected into the center of a reaction chamber operating at temperatures as high as 1500°C and possibly containing as much as 0.5 Torr of xenon fill gas. The DT layer must remain highly symmetric, have a smooth inner ice surface finish, and reach the chamber center (CC) at a temperature of about 18.5 K. This target must be positioned at the center of the chamber with a placement accuracy of ±5 mm. The accuracy of alignment of the laser driver beams and the target in its final position must be within ±20 µm. All this must be repeated six times per second. The method proposed to meet these requirements is injecting the targets into the reaction chamber at high speed (~400 m/s), tracking them, and hitting them on the fly with steerable driver beams. The challenging scientific and technological issues associated with this task are being addressed through a combination of analyses, modeling, materials property measurements, and demonstration tests with representative injection equipment. Measurements of relevant DT properties are planned at Los Alamos National Laboratory. An experimental target injection and tracking system is now being designed to support the development of survivable targets and demonstrate successful injection scenarios. Analyses of target heating are underway. Calculations have shown that the direct drive target must have a highly reflective outer surface to prevent excess heating by thermal radiation. In addition, heating by hot chamber fill gas during injection far outweighs the thermal radiation. It is concluded that the dry-wall, gasfilled reaction chambers must have gas pressures and wall temperatures less than previously assumed in order to prevent excessive heating in the current direct drive target designs. An integrated power plant systems study to address this issue has been initiated.

Glass capsules were imploded in direct drive on the OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)] to look for anomalous degradation in deuterium/tritium (DT) yield and changes in reaction history with H3e addition. Such anomalies have previously been reported for D/H3e plasmas but had not yet been investigated for DT/H3e. Anomalies such as these provide fertile ground for furthering our physics understanding of inertial confinement fusion implosions and capsule performance. Anomalous degradation in the compression component of yield was observed, consistent with the “factor of 2” degradation previously reported by Massachusetts Institute of Technology (MIT) at a 50% H3e atom fraction in D2 using plastic capsules [Rygg, Phys. Plasmas 13, 052702 (2006)]. However, clean calculations (i.e., no fuel-shell mixing) predict the shock component of yield quite well, contrary to the result reported by MIT but consistent with Los Alamos National Laboratory results in D2/H3e [Wilson et al., J. Phys.: Conf. Ser. 112, 022015 (2008)]. X-ray imaging suggests less-than-predicted compression of capsules containing H3e. Leading candidate explanations are poorly understood equation of state for gas mixtures and unanticipated particle pressure variation with increasing H3e addition.

Abstract. Continued advances in the design of ignition targets have stimulating new development paths for target fabrication, with potentially important simplifications for fielding cryogenic ignition targets for the National Ignition Facility. Including graded dopants in ablators as well as optimizing capsule and fuel layer dimensions increase implosion stability. This has led to developments of micron-scale fill tubes to fill and field the targets. Rapid progress has been made in development of the graded dopant layers in capsules as well as their characterization, in fabrication methods for micro-fill-tubes, and in fuel fill control with these fill tubes. Phase-contrast x-ray radiography has allowed characterization of fuel layers in beryllium targets.

A central feature of an Inertial Fusion Energy (IFE) power plant is a target that has been compressed and heated to fusion conditions by the energy input of the driver. The technology to economically manufacture and then position cryogenic targets at chamber center is at the heart of futureIFE power plants. For direct drive IFE (laser fusion) energy is applied directly to the surface of a spherical CH polymer capsule containing the deuterium-tritium (DT) fusion fuel at approximately 18 K. For indirect drive (heavy ion fusion, HIF) the target consists of a similar fuel capsule within a cylindrical metal container or "hohlraum" which converts the incident driver energy into xrays to implode the capsule. For either target, it must be accurately delivered to the target chamber center at a rate of about 5-10 Hz, with a precisely predicted target location. Future successful fabrication and injection systems must operate at the low cost required for energy production (about $0.25/target, about 10 4 less than current costs).Z-pinch driven IFE (ZFE) utilizes high current pulses to compress plasma to produce x-rays that indirectly heat a fusion capsule. ZFE target technologies utilize a repetition rate of about 0.1 Hz with a higher yield This paper provides an overview of the proposed target methodologies for laser fusion, HIF, and ZFE, and summarizes advances in the unique materials science and technology development programs