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Title: Foot-pulse radiation drive necessary for ICF ignition capsule demonstrated on Z generator

Abstract

Implosion and ignition of an indirectly-driven ICF capsule operating near a Fermi-degenerate isentrope requires initial Planckian-radiation-drive temperatures of 70-to-90 eV to be present for a duration of 10-to-15 ns prior to the main drive pulse. Such capsules are being designed for high pulsed-power generators. This foot-pulse drive capability has been recently demonstrated in a NIF-sized ({phi} = 6-mm 1 = 7-mm), gold hohlraum, using a one-sided static-wall hohlraum geometry on the Z generator. The general arrangement utilized nested tungsten-wire arrays of radii (mass) 20 mm (2 mg) and 10 mm (1 mg) that had an axial length of {approximately} 10 mm. The arrays were driven by a peak current of {approximately} 21 MA and were made to implode on a 2-{micro}m-thick Cu annulus (mass = 4.5 mg), which had a radius of 4 mm and was filled with a low-density CH foam, all centered about the z-axis. The gold hohlraum was mounted on axis and above the Cu/foam target. A 2.9-mm-radius axial hole between the top of the target and hohlraum permitted the x-rays generated from the implosion to enter the hohlraum. The radiation within the hohlraum was monitored by viewing the hohlraum through a 3-mm diameter hole on themore » lateral side of the hohlraum with a suite of diagnostics.The radiation entering the hohlraum was estimated by an additional suite of on-axis diagnostics, in a limited number of separate shots, when the hohlraum was not present. Additionally, the radiation generated outside the Cu annulus was monitored, for all shots, through a 3-mm diameter aperture located on the outside of the current return can. In the full paper, the characteristics of the radiation measured from these diagnostic sets, including the Planckian temperature of the hohlraum and radiation images, will be discussed as a function of the incident wire-array geometry (single vs nested array and array mass), target length (10, or 20 mm), annulus material (Cu, Au, or nothing), and CH-foam-fill density (10, 6, 2.5, or 0 mg/cc). Comparisons of a limited number of these variations with 1-D and 2-D rad-hydro and 3-D radiosity simulations will also be reviewed. Lastly, hole closure in the on- and off-axis apertures will be discussed.« less

Authors:
; ;  [1]
  1. and others
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (US)
Sponsoring Org.:
USDOE
OSTI Identifier:
20034273
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: 1999 IEEE International Conference on Plasma Science, Monterey, CA (US), 06/20/1999--06/24/1999; Other Information: PBD: 1999; Related Information: In: The 26th IEEE international conference on plasma science, 342 pages.
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; IMPLOSIONS; INDIRECT DRIVE ICF; THERMONUCLEAR IGNITION; X-RAY SOURCES; PLASMA DIAGNOSTICS

Citation Formats

Sanford, T W.L., Olson, R E, and Chandler, G A. Foot-pulse radiation drive necessary for ICF ignition capsule demonstrated on Z generator. United States: N. p., 1999. Web.
Sanford, T W.L., Olson, R E, & Chandler, G A. Foot-pulse radiation drive necessary for ICF ignition capsule demonstrated on Z generator. United States.
Sanford, T W.L., Olson, R E, and Chandler, G A. Thu . "Foot-pulse radiation drive necessary for ICF ignition capsule demonstrated on Z generator". United States.
@article{osti_20034273,
title = {Foot-pulse radiation drive necessary for ICF ignition capsule demonstrated on Z generator},
author = {Sanford, T W.L. and Olson, R E and Chandler, G A},
abstractNote = {Implosion and ignition of an indirectly-driven ICF capsule operating near a Fermi-degenerate isentrope requires initial Planckian-radiation-drive temperatures of 70-to-90 eV to be present for a duration of 10-to-15 ns prior to the main drive pulse. Such capsules are being designed for high pulsed-power generators. This foot-pulse drive capability has been recently demonstrated in a NIF-sized ({phi} = 6-mm 1 = 7-mm), gold hohlraum, using a one-sided static-wall hohlraum geometry on the Z generator. The general arrangement utilized nested tungsten-wire arrays of radii (mass) 20 mm (2 mg) and 10 mm (1 mg) that had an axial length of {approximately} 10 mm. The arrays were driven by a peak current of {approximately} 21 MA and were made to implode on a 2-{micro}m-thick Cu annulus (mass = 4.5 mg), which had a radius of 4 mm and was filled with a low-density CH foam, all centered about the z-axis. The gold hohlraum was mounted on axis and above the Cu/foam target. A 2.9-mm-radius axial hole between the top of the target and hohlraum permitted the x-rays generated from the implosion to enter the hohlraum. The radiation within the hohlraum was monitored by viewing the hohlraum through a 3-mm diameter hole on the lateral side of the hohlraum with a suite of diagnostics.The radiation entering the hohlraum was estimated by an additional suite of on-axis diagnostics, in a limited number of separate shots, when the hohlraum was not present. Additionally, the radiation generated outside the Cu annulus was monitored, for all shots, through a 3-mm diameter aperture located on the outside of the current return can. In the full paper, the characteristics of the radiation measured from these diagnostic sets, including the Planckian temperature of the hohlraum and radiation images, will be discussed as a function of the incident wire-array geometry (single vs nested array and array mass), target length (10, or 20 mm), annulus material (Cu, Au, or nothing), and CH-foam-fill density (10, 6, 2.5, or 0 mg/cc). Comparisons of a limited number of these variations with 1-D and 2-D rad-hydro and 3-D radiosity simulations will also be reviewed. Lastly, hole closure in the on- and off-axis apertures will be discussed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {7}
}

Conference:
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