We are carrying out a multidisciplinary multi-institutional program to develop the scientific and technical basis for inertial fusion energy (IFE) based on laser drivers and direct-drive targets. The key components are developed as an integrated system, linking the science, technology, and final application of a 1000-MWe pure-fusion power plant. The science and technologies developed here are flexible enough to be applied to other size systems. The scientific justification for this work is a family of target designs (simulations) that show that direct drive has the potential to provide the high gains needed for a pure-fusion power plant. Two competing lasers are under development: the diode-pumped solid-state laser (DPPSL) and the electron-beam-pumped krypton fluoride (KrF) gas laser. This paper will present the current state of the art in the target designs and lasers, as well as the other IFE technologies required for energy, including final optics (grazing incidence and dielectrics), chambers, and target fabrication, injection, and tracking technologies. All of these are applicable to both laser systems and to other laser IFE-based concepts. However, in some of the higher performance target designs, the DPPSL will require more energy to reach the same yield as with the KrF laser.

The High Average Power Laser (HAPL) program is focusing on the development of laser IFE power plants based on lasers, direct-drive targets and dry wall chambers. One key issue is the survival of the chamber wall under the ion threat spectra (representing ˜25% of the yield energy). The possibility of steering the ions away from the chamber to specially-designed dump chambers using magnetic intervention is being investigated. This brings up the intriguing possibility of utilizing a liquid wall to accommodate the ion fluxes in the dump chamber provided the right measures are taken to prevent the liquid from contaminating the main chamber. This paper covers the initial assessment of different magnetic configurations for a laser IFE chamber. Their key characteristics are described; results of the supporting design analyses are summarized; and the major findings and issues are highlighted.

The possibility of utilizing magnetic intervention (MI) in a laser-driven inertial fusion energy (IFE) dry wall chamber is being considered to steer away the ions from the chamber wall to more readily accessible and replaceable dump regions at the equator and poles. This paper summarizes the current status of this study, describing the overall MI chamber core configuration and layout and highlighting the key design and analysis results for the different components.

A possible way to address the issue of dry wall survival in a Laser IFE chamber is to use magnetic diversion in order to steer away the ions from the chamber wall (representing -25-30% of the yield energy). A cusp magnetic field is imposed on to the chamber; the ions from the micro-explosion are trapped within the magnetic field and are directed to more readily accessible and replaceable dump regions at the equator and poles. A large fraction of the magnetic energy can be dissipated in the chamber walls if an electrically resistive structural material is used. An advanced blanket based on a self-cooled liquid breeder (e.g.Pb-17Li or flibe) and SiCf/SiC structure has been proposed for this purpose and a scoping design study performed as part of the High Average Power Laser program effort This paper summarizes the results of this scoping study, and highlights the advantages of such a concept as well as the key issues that need to be addressed by R&D.

A conceptual design has been developed for the recovery of un-expended fuel, ash, and associated post-detonation products from a ~ 2 GW IFE power reactor. The conceptual design incorporates systems for the safe, efficient collection, processing, and purification of IFE plasma exhaust fuel components. The system has been designed and sized such that tritium bred within blankets can also be collected, processed, and introduced into the fuel cycle. The system is nominally sized to process ~2 kg of tritium per day and is designed to link directly to the target chamber mechanical pumping system. The plasma exhaust can be directly processed from the exhaust of the vacuum pumping system or can be processed in batch mode from buffer vessels in the receiving and analysis system (RAS). Systems for the accurate measurement of material in-process (MIP) have been included. Design emphasis is on safety, reliability, redundancy, and efficiency in order to maximize availability. The primary goal of the fuel recovery system (FRS) design is to economically recycle components of IFE fuel back to the target manufacturers in a fashion by which fuel components are rapidly made available for re-use thus lowering the total active inventory. The FRS design is presented as a facility sub-system in the context of supporting the safe and efficient operation of the IFE target chamber.

Energetic ions are produced in the thermonuclear explosion of a target in a direct drive laser-driven inertial fusion energy systems. These ions will be deposited in the first wall of the chamber, potentially leading to degradation of the surface. The magnetic intervention concept imposes a cusp magnetic field on the chamber, directing the ions to dump regions where their energy can be removed from the system. A computational assessment is carried out to examine the exchange of ion energy with the applied magnetic field and to determine the both the ion energy spectrum of the escaping ions and the dimensions of the escape regions.

A conceptual design for a magnetic intervention system is presented in support of a 2 GW IFE direct drive fusion power reactor. The system is designed employing a cusp field to deflect ions generated by an IFE implosion away from the first wall of the reactor core and into specifically designed ion dumps. The magnetic coil system will employ liquid helium cooled 5083 Aluminum alloy casing on a Rutherford NbTi cable. The cables are configured as four double pancakes with a 5083 Aluminum alloy case for structural support. The conceptual design and corresponding preliminary load and field calculations will be presented.

This paper covers the results of a scoping study to assess the possible application of magnetic diversion to a laser IFE reactor. Its impact on the engineering design and performance of the reactor is discussed, key issues are identified, and the findings from this assessment are summarized.

Summary form only given. A novel design for an inductively coupled, rectangular plasma source is described. The design encompasses several key issues of large area thin film growth by CVD: structural integrity; electrostatic screening; substrate temperature control; and maximal growth surface. A test reactor has been utilized to grow diamond films over/spl sim/1800 cm/sup 2/ at 13 MHz and /spl sim/1 Torr pressure with 45 kW coupled power. The design is readily scalable to larger areas. To analyze the axial plasma uniformity, a 2-D simulation model is presented. The electromagnetic coupling, non-equilibrium plasma chemistry, and multi-species diffusion are self-consistently treated. In this 2-D approach, the slotted Faraday screen behaves as a diamagnetic medium in transmitting the magnetic field. Results are compared with experimental data for the hydrogen plasma extent, electron, and gas temperatures. Neutral gas thermal conduction and hydrogen recombination dominate the energy deposition to the wall, and in turn govern the plasma length. A tradeoff between quality and growth area is predicted for the reactor as the pressure is decreased.

A novel design for an inductively coupled, rectangular plasma source is described. The design encompasses several key issues of large area thin film growth by chemical vapor deposition: structural integrity, electrostatic screening, substrate temperature control and maximal growth surface. A test reactor has been utilized to grow diamond films over /spl sim/1800 cm/sup 2/ at 13 MHz and /spl sim/1 torr pressure with 45 kW coupled power. The design is readily scalable to larger areas. To analyze the axial plasma uniformity, a two-dimensional (2-D) simulation model is presented. The electromagnetic coupling, nonequilibrium plasma chemistry and multispecies diffusion are self-consistently treated. In this 2-D approach, the slotted Faraday screen behaves as a diamagnetic medium in transmitting the magnetic field. Results are compared with experimental data for the hydrogen plasma extent, electron and gas temperatures. Neutral gas thermal conduction and hydrogen recombination dominate the energy deposition to the wall and in turn govern the plasma length. A tradeoff between quality and growth area is predicted for the reactor as the pressure is decreased.

Summary form only given, as follows. An electrostatic shield in the form of a hollow metal cylinder is often placed between the exciting coil and the discharge tube of an inductively coupled plasma system in order to screen the plasma from the electric field of the coil. Such fields can, under some circumstances, have a deleterious effect on the process for which the plasma is being used. It is not generally realized that the electrostatic shield can also lead to a significant reduction of the r.f. magnetic field inside the tube as well as altering its axial distribution. This effect needs to be considered in detailed modeling of inductively coupled plasma system and is of practical importance in determining the impedance the plasma presents to the r.f. generator. We have studied the effect by measuring the r.f. magnetic field inside and outside metal cylinders with different slot configurations and have developed electromagnetic models for both thin and thick shields which give good agreement with the observations. In one of the models the shield can be treated as an axisymmetric diamagnetic medium thereby allowing a 2D treatment of an intrinsically 3D problem. The thick shield is relevant to high power systems in which the discharge tube itself is a thick-walled, water cooled, slotted metal cylinder (i.e., a cold crucible). Plasma coupling in such a system has been compared with coupling in a system with dielectric tube and the predictions of the model have been verified.