2005 47th Annual Meeting of the Division of Plasma Physics
Monday–Friday, October 24–28, 2005;
Denver, Colorado
Session UI1: ICF Ignition
9:30 AM–12:30 PM,
Friday, October 28, 2005
Adam's Mark Hotel
Room: Plaza Ballroom ABC
Chair: Denise Hinkel, Lawrence Livermore National Laboratory
Abstract ID: BAPS.2005.DPP.UI1.6
Abstract: UI1.00006 : Pathway to a lower cost high-repetition IFE ignition facility
12:00 PM–12:30 PM
Preview Abstract
Abstract
Author:
Stephen Obenschain
(Plasma Physics Division, U.S. Naval Research Laboratory)
We have identified an attractive path to develop the science and
technology for fusion energy based on direct-drive pellet
designs that substantially reduce the needed laser energy. A
power plant based on laser fusion will require pellet energy
gains of about 100 to overcome inefficiencies in the laser and
power generation. For directly-driven targets this probably
requires energies of at least one MegaJoule. However, many of
the key science and engineering tasks could be accomplished with
ignition and lesser gains. If one increases the pellet implosion
velocity from the nominal 300 km/sec in high gain designs to 400
to 500 km/sec, one can obtain ignition and moderate gains at
substantially reduced laser energy. This higher velocity can be
obtained by increasing the distance over which the pellet shell
is accelerated. But this approach leads to thin large-diameter
pellet shells and the implosion is more likely to be disrupted
by hydrodynamic instability. One can alternately obtain higher
velocity by increasing the laser irradiance and thereby produce
higher ablation pressure. This approach allows high-velocity
implosion of relatively thick-shelled smaller-diameter targets
that are much more resistant against hydrodynamic instability.
The Krypton Fluoride (KrF) laser has substantial advantages
towards implementing this approach. Its 248 nm deep-UV
wavelength and very broad bandwidth suppress the laser-plasma
instability that limits usable peak irradiance. The short laser
wavelength also gives higher pressure and more efficient
absorption. Our one-dimensional simulations using a KrF driver
predict energy gains of 20 with 250 kJ laser energy and gains
above 50 at 500 kJ. These pellet designs employ mechanisms that
increase hydrodynamic stability. This approach opens the
opportunity for a relatively small high-repetition KrF-based
laser fusion facility that would be useful for developing and
testing fusion energy science and technologies. Progress in the
analysis of the pellets and implications for a faster-track IFE
program will be discussed.
This work was supported by the U.S. Department of Energy, NNSA.
Work in collaboration with the researchers in the NRL Laser
Fusion Program and the High Average Power Laser (HAPL) Program.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.DPP.UI1.6