Progress and critical issues for IFE blanket and chamber research
B. Grant Logan · Wayne R. Meier · Ralph W. Moir · Mohamed Abdou · Per F. Peterson · Gerald L. Kulcinski · Mark S. Tillack · Jeffery F. Latkowski · David Petti · Kenneth R. Schultz · Art Nobile
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In one page
An inertial fusion power plant works by dropping a fuel capsule into a chamber about five times a second and hitting it with a driver — a laser, or a beam of heavy ions — hard enough to make it burn. Everything else is the chamber. Grant Logan and ten colleagues, from Livermore, Los Alamos, Idaho, General Atomics, Los Angeles, Berkeley, San Diego and Wisconsin, wrote this invited paper for the fifth fusion nuclear technology symposium in Rome to set out what that chamber has to do and what nobody yet knows how to do. Their list of requirements is five items long: keep the chamber fit for the next target and the next beam; protect the walls and the optics so they last for years; take the heat out at a temperature worth converting to electricity while breeding the tritium fuel back; make targets precise and cheap and inject them on time; and keep the radioactive inventory small enough that no credible accident would require evacuating the public.
Why it matters hereChapter 18 is about the machines, and this is the paper that says which parts of an inertial fusion machine are still open questions rather than engineering. It is also a map of a real programme with real hardware — water-jet hydraulics rigs, shock tubes, gas guns, laser damage stands — which is the form the site’s evidence ladder likes best: named institutions, named experiments, and a stated next measurement for each.
What it claims
01The five basic technical system requirements for any inertial fusion chamber and target system, in the authors’ order: maintain chamber conditions suitable for target injection, driver beam propagation and high-gain ignition at pulse rates around five per second; protect the chamber walls and driver beam interfaces so they last several years, ideally the life of the plant, or can be replaced in sections; extract the fusion energy with high-temperature coolants for efficient conversion to electricity while regenerating the tritium fuel with a small just-in-time inventory; manufacture precision targets at economically low cost and inject them accurately into the chamber centre at the same few hertz; and hold radioactive waste generation, inventory and possible release fractions low enough that no public evacuation is needed in worst-case accidents.Section 2 IFE Power Plant Requirements, items a to e
Designed, not yet built02The United States programme narrowed to two options for its first four-year phase, because with limited resources only a few can be tested at once: renewable liquid-wall chambers of the HYLIFE-II kind, with indirect-drive targets and ion accelerator drivers; and dry-wall chambers of the SOMBRERO kind, with direct-drive targets and lasers, either krypton-fluoride gas lasers or diode-pumped solid-state lasers. The work is coordinated through the Virtual Laboratory for Technology, formed by the Department of Energy in December 1998, and was scoped by about forty researchers meeting at Pleasanton, California, on 18 March 1999.Sections 2 and 3, opening paragraphs
On the bench now03The open questions for the thick-liquid-wall line, stated as questions: can thick liquid walls be formed, maintained and evacuated from the chamber, and can vapour condensation, droplet clearing and flow recovery keep up with five shots a second? Can the superconducting quadrupole focusing magnet arrays be made physically consistent with the chamber and target solid-angle limits, given that recent designs call for of order one hundred or more beams from each of two sides? Can hohlraums with foam x-ray converters and an internal cryogenic capsule mount be mass-manufactured to target precision for less than three tenths of a United States dollar each, and survive the acceleration of injection? And can a site-boundary dose near one rem, a hundredth of a sievert, be met for credible accidents including spills of activated liquid coolant?Section 3 Critical Issues, thick liquid wall list, items 1 to 4
What to watch04The open questions for the dry-wall line: can the first-wall blanket tolerate the uncertainty in surface ablation rates, thermal conductivity loss and swelling from neutron damage and pulsed x-ray heating of the chamber gas? Can the final optics survive more than one hundred million shots of laser, neutron, x-ray and debris damage and still hold microradian pointing accuracy under pulsed heating and gas shocks? Can the laser propagate through gas dense enough to protect the wall? And can a direct-drive capsule survive injection into a hot chamber within the temperature limits that keep its fuel layer smooth? The materials answer the authors name is a four-dimensional carbon weave more tolerant of neutron swelling, or aluminium-loaded silicon-carbide composites, if their thermal conductivity can be pushed to between fifty and one hundred watts per metre-kelvin at fifteen hundred to two thousand degrees Celsius.Section 3, dry-wall list items 1 to 4, and Section 4.2 Dry Wall Chamber R and D
What to watch05The hardware that already existed when the paper was written, and this is the part that makes it a programme rather than a study: a thick-liquid hydraulics facility at Berkeley using water jets to simulate molten-salt Flibe jets at half to quarter geometric scale with matching Reynolds, Froude and Weber numbers; the Popoff experiment at Los Angeles measuring the fracture strength of liquid lithium, lead, Flibe and lithium-lead under ten-nanosecond laser loading; a large gas-driven shock tube at Wisconsin testing blast flow around chamber structures; a ten-hertz laser damage stand at San Diego establishing fluence limits for final optics; a gas gun at Berkeley that had already demonstrated hohlraum injection at one hundred metres per second to five millimetre accuracy, tracked for beam steering within two hundred micrometres; and the FLIQURE experiment being designed at Idaho to measure radionuclide mobilisation from Flibe.Sections 4.1 to 4.5 with Figures 1 to 5
On the bench now06The paper’s own summary judgement: the feasibility of inertial fusion energy depends on solving the chamber and target technology issues just as much as it depends on high-gain targets and efficient, high-pulse-rate drivers. Phase I is assessment studies, small-scale experiments and simulations; Phase II would demonstrate more integrated non-nuclear tests closer to full fusion chamber scale; and the authors expect integrated systems analysis to be needed along the way, because findings in one area will call the compatibility of the others into question.Section 4 opening, Section 4.6 Integrated Systems Analysis, and Section 5 Summary
Designed, not yet built
The way in
https://doi.org/10.1016/s0920-3796(00)00221-0PUBLICATION. Fusion Engineering and Design, volumes 51 to 52, pages 1095 to 1101, November 2000 — an invited paper given at the 5th International Symposium on Fusion Nuclear Technology, Rome, 19 to 24 September 1999. The journal version is closed at Elsevier, whose only registered licence for this DOI is a text-and-data-mining licence, which is not a reading or redistribution licence. SOURCE READ, AND WHY NOTHING IS REPRODUCED. The Lawrence Livermore preprint of the same paper, UCRL-JC-134976, dated 23 June 1999, is public at the Department of Energy Office of Scientific and Technical Information as record 13884, and that twelve-page PDF was retrieved and read in full on 2026-09-09. Its cover carries the opposite of a public-release statement: it says that since changes may be made before publication, the preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. This sheet therefore stays summary-only and reproduces no text of the work at all — not the body, and not the abstract, although the abstract deposited with the Office of Scientific and Technical Information and mirrored by the University of North Texas Digital Library was read. Every claim below is located by the preprint’s own numbered section or figure. The work was performed under the auspices of the United States Department of Energy by Lawrence Livermore National Laboratory under contract W-7405-Eng-48, sponsored by the Office of Energy Research; the standard Livermore disclaimer on the preprint states that neither the United States Government nor the University of California makes any warranty or assumes any liability for the information, so this is a contractor document rather than a work of the United States Government, and it is not promoted to public domain. AFFILIATIONS as printed on the preprint: Logan, Meier, Moir and Latkowski, Lawrence Livermore National Laboratory; Abdou, University of California at Los Angeles, Mechanical and Aerospace Engineering; Kulcinski, University of Wisconsin at Madison; Peterson, University of California at Berkeley, Nuclear Engineering; Tillack, University of California at San Diego; Schultz, General Atomics, San Diego; Petti, Idaho National Engineering and Environmental Laboratory; Nobile, Los Alamos National Laboratory. The registry recorded the first author’s name as ‘B.Grant Logan’, a Crossref deposit artefact; it is B. Grant Logan. A second OSTI identifier, AT5015032, appears on the record alongside the report number.
How to cite it
B. Grant Logan, Wayne R. Meier, Ralph W. Moir, Mohamed Abdou, Per F. Peterson, Gerald L. Kulcinski, Mark S. Tillack, Jeffery F. Latkowski, David Petti, Kenneth R. Schultz, Art Nobile (2000) Progress and critical issues for IFE blanket and chamber research. doi:10.1016/s0920-3796(00)00221-0
Where it sits in the curriculum
Fusion machines: pinches, focus devices and inertial drivers