Robert R. Peterson

Inertial fusion energy target output and chamber response: Calculations and experiments

The emission of photons and energetic ions by the burn and subsequent explosion of inertial fusion energy (IFE) targets poses a threat to the survival of the target chambers in future IFE power plants. Immediately after the deposition of target output, the chamber can experience sufficient heating to cause vaporization, melting, and shock loading on chamber walls. Until high-yield targets can be ignited in laboratory experiments, predictions of the nature of the target output and the response of the target chamber must be made with radiation-hydrodynamics computer codes that need to be validated with relevant smaller scale experiments. Physical models of equation of state, opacity, and radiation transport are in special need of validation. Issues of target output and chamber response requiring experiments and computer modeling are discussed and initial results from experiments are presented. Calculations of x ray and debris output from direct-drive IFE targets are shown and sensitivity of the output spect...

Observation of reduced beam deflection using smoothed beams in gas-filled hohlraum symmetry experiments at Nova

Execution and modeling of drive symmetry experiments in gas-filled hohlraums have been pursued to provide both a better understanding of radiation symmetry in such hohlraums and to verify the accuracy of the design tools which are used to predict target performance for the National Ignition Facility (NIF) [J. Lindl, Phys. Plasmas 2, 3933 (1995)]. In this paper, the results of a series of drive symmetry experiments using gas-filled hohlraums at the Nova laser facility [C. Bibeau et al., Appl. Opt. 31, 5799 (1992)] at Lawrence Livermore National Laboratory are presented. A very important element of these experiments was the use of kineform phase plates (KPP) to smooth the Nova beams. The effect of smoothing the ten Nova beams with KPP phase plates is to remove most of the beam bending which had been observed previously, leaving a residual bending of only 1.5°, equivalent to a 35 μm pointing offset at the hohlraum wall. The results show that the symmetry variation with pointing of implosions in gas-filled ho...

Design Issues for a Light Ion Beam LMF Driver

The U.S. Department of Energy is conducting a preliminary study of a Laboratory Microfusion Facility (LMF). A major goal of the LMF is the development of high-gain ICF targets in a laboratory environment. Light ion beams are a candidate for the LMF driver. This paper discusses initial results from a study of a light ion beam driver for the LMF. An overview of the LMF design concept is presented together with key design issues for the various subsystems.

The effect of irradiation creep, swelling, wall erosion and embrittlement on the fatigue life of a Tokamak first wall

Abstract A lifetime methodology has been developed which couples the long-term stress history for a generic fir4st wall element to a two-dimensional fatigue crack growth calculation, while including, in a self-consistent manner, the detrimental effects of radiation damage. The reduction in fracture toughness due to embrittlement can reduce lifetimes by as much as a factor of 10 by accelerating stage II fatigue crack growth and enhancing the potential for brittle fracture. Swelling and irradiation creep appear not to be life-limiting, and a certain amount of wall erosion is found to enhance first wall lifetimes.

Overview of the LIBRA light ion beam fusion conceptual design

The LIBRA light ion beam fusion commercial reactor study is a self-consistent conceptual design of a 330 MWe power plant with an accompanying economic analysis. Fusion targets are imploded by 4 MJ shaped pulses of 30 MeV Li ions at a rate of 3 Hz. The target gain is 80, leading to a yield of 320 MJ. The high intensity part of the ion plate is delivered by 16 diodes through 16 separate z-pinch plasma channels formed in 100 torr of helium with trace amounts of lithium. The blanket is an array of porous flexible silicon carbide tubes with Li/sub 17/Pb/sub 83/ flowing downward through them. These tubes (INPORT units) shield the target chamber wall from both neutron damage and the shock overpressure of the target explosion. The target chamber is self-pumped by the target explosion generated overpressure into a surge tank partially filled with Li/sub 17/Pb/sub 83/ that surrounds the target chamber. This scheme refreshes the chamber at the desired 3 Hz frequency without excessive pumping demands. The blanket multiplication is 1.2 and the tritium breeding ratio is 1.4. The direct capital cost of LIBRA is estimated to be

Plasma gun experiments and modeling of disruptions

2200/kWe.

Energy deposition and shock wave evolution from laser-generated plasma expansions

Abstract Potentially high erosion due to ablation from plasma disruptions looms as a nemesis for advanced fusion devices such as ITER. Under some conditions, it is believed that the material ablated during a disruption forms a “vapor shield” that mitigates subsequent ablation. This paper presents new experimental data that identifies an absorption surface in the ablating plasma that is above the irradiated armor surface. We also present a summary of progress in modeling using a 1-D Lagrangian hydrodynamics code. Experimental erosion data will be reviewed from the PLADIS facility, a plasma gun at the University of New Mexico on several materials, including Be, tungsten, copper, graphites. Profile measurements of the crater topology showed the eroded Be surface to be much rougher than that of carbon and to demonstrate erosion rates that were almost factors of four greater than graphite. Plasma guns at the D.V. Efremov Scientific Research Institute and at TRINITI, both in the Russian Federation, are being utilized to confirm spectroscopic vapor shield data.

Flexible database-driven opacity and spectrum calculations

One‐dimensional radiation‐hydrodynamics calculations have been performed to study the structure and evolution of blast waves resulting from laser‐generated plasma expansions. The results are compared with experimental data obtained at the Naval Research Laboratory [Laser Interaction and Related Plasma Phenomena (Plenum, New York, 1986), Vol. 7, pp. 857–877]. In these calculations, target ions expand into a stationary background gas with an initial pressure ranging from 25 mTorr–5 Torr. Because the stopping ranges of the target ions are comparable to the dimensions of the shock, the blast wave properties are sensitive to the ion stopping cross sections. In some calculations, the effects of radiation transport were neglected in order to assess its importance. The results presented in this paper are in generally good agreement with available experimental data, and indicate that the observed blast wave properties can be accounted for by using a classical collision model to describe the interaction between the...

Dry wall chamber issues for the SOMBRERO laser fusion power plant

The integration of computational atomic physics and information technology can provide flexible, convenient tools for high energy density physicists both computational and experimental. In this work, a flexible atomic database is applied to plasma opacity and spectrum calculations. Multiple atomic data models, such as screened hydrogenic, non-relativistic (ATBASE) and jj split relativistic (RSSUTA), are seamlessly incorporated into the software architecture. High performance parallel programming is applied to accelerate the computation of both the atomic data and the opacity calculations. The user interface is graphical and provided as an easy to use and convenient method to access the data and diagnose the calculations. We present opacity and spectrum results for Kr and Nb plasmas as examples of this new capability.

LIBRA-LiTE: A 1000 MWe reactor

A reassessment of the SOMBRERO laser driven fusion power plant that was designed in 1990-91 has been conducted. New information and analysis has confirmed most of the original design decisions except that the tritium inventory in the blanket may be larger than originally calculated. Possible methods of lowering the tritium inventory are described along with a discussion of the critical issues that still remain 10 years after the original design was completed.