Implosion hydrodynamics of fast ignition targets

Journal Article · Sun May 15 04:00:00 EDT 2005 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.1896952· OSTI ID:20736604

Stephens, R B; Nikroo, A; Smith, J ^[1]; Hatchett, S P; Tabak, M ^[2]; Stoeckl, C; Bonino, M; Sangster, T C ^[3]; Shiraga, H; Fujioka, S; Tanaka, K A ^[4]; Petrasso, R ^[5]

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1. General Atomics, San Diego, California 92186-5608 (United States)
2. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
3. Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)
4. Institute for Laser Engineering, Osaka University, Osaka, 565-0871 (Japan)
5. Massachussetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

The fast ignition (FI) concept requires the generation of a compact, dense, pure fuel mass accessible to an external ignition source. The current base line FI target is a shell fitted with a reentrant cone extending to near its center. Conventional direct- or indirect-drive collapses the shell near the tip of the cone and then an ultraintense laser pulse focused to the inside cone tip generates high-energy electrons to ignite the dense fuel. A theoretical and experimental investigation was undertaken of the collapse of such targets, validating modeling, and exploring the trade-offs available, in such an asymmetric geometry, to optimize compaction of the fuel and maintain the integrity of the cone. The collapse is complex. Away from the cone, the shell collapses much as does a conventional implosion, generating a hot, low-density inner core. But because of the open side, hot plasma exhausts out toward the tip of the cone. This hot plasma is advantageous for implosion diagnostics; it can provide protons for angular dependent measurements of the shell wall, neutrons for temperature measurements, and self-emission for contamination measurements. But for FI it is a liability; the hot, low-density inner core impedes the compaction of the cold fuel, lowering the implosion/burn efficiency and the gain. Approaches to optimizing this shell design are discussed.

• OSTI ID: 20736604
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 12; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
HOT PLASMA
LASER IMPLOSIONS
LASER-RADIATION HEATING
PLASMA DIAGNOSTICS
TEMPERATURE MEASUREMENT
THERMONUCLEAR FUELS
THERMONUCLEAR IGNITION