摘要:

Foil targets irradiated by the Naval Research Laboratory Nike KrF laser were imaged in the x-ray region with two-dimensional spatial resolution in the 2–10 &mgr;m range. The images revealed the smoothness of the emission from target and backlighter foils, the acceleration of the target foils, and the growth of Rayleigh–Taylor instabilities that were seeded by patterns on the irradiated sides of CH foils.

ISSN:0034-6748    

DOI:10.1063/1.1147796

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We propose a new “threshold” bubble chamber detector for measurement of knock-on neutron tails. These energetic neutrons result from fusion reactions involving energetic fuel ions created by alpha knock-on collisions in tokamak and other magnetic confinement experiments, and by both alpha and neutron knock-on collisions in inertial confinement fusion (ICF) experiments. The energy spectrum of these neutrons will yield information on the alpha population and energy distribution in tokamaks, and on alpha target physics and&rgr;Rmeasurements in ICF experiments. The bubble chamber should only detect neutrons with energies above a selectable threshold energy controlled by the bubble chamber pressure. The bubble chamber threshold mechanism, detection efficiency, and proposed applications to the International Thermonuclear Experimental Reactor and National Ignition Facility experiments will be discussed. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147798

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We use an unresolved transition array model to investigate the opacities of high-Zmaterials and their mixtures which are of interest to indirect-drive inertial confinement fusion hohlraum design. In particular, we report on calculated opacities for pure Au, Gd, and Sm, as well as Au–Sm and Au–Gd mixtures. Our results indicate that mixtures of Au–Gd and Au–Sm can produce a significant enhancement in the Rosseland mean opacity. Radiation hydrodynamics simulations of Au radiation burnthrough are also presented, and compared with NOVA experimental data. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147799

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present a variable-frequency variant of the complex demodulation technique. Complex demodulation is the digital equivalent of heterodyne detection, in which the input signal is multiplied by a carrier oscillation {exp(−i&ohgr;mt)} of modulation frequency &ohgr;mand then low-pass filtered. The time-dependent amplitude and relative phase can then be computed from the filtered demodulate. This technique fails when the frequency of oscillation differs from the modulation frequency by more than the cutoff frequency of the low-pass filter. We modified the standard technique by computing iteratively a time-dependent modulation frequency{&ohgr;m(t)}that tracks the signal frequency to within ±0.1&percent; of the Nyquist frequency. This small difference frequency allows the use of very narrow filter bandwidths for the study of narrow-band oscillations with improved signal-to-noise ratio. We apply this analysis tool to Mirnov oscillations measured by a magnetic probe and show the time variation of the amplitude of the fundamental and harmonic frequencies during a plasma current ramp down. Future work will involve the application of this technique to ECE measurements. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147748

出版商:AIP    

年代:1997

数据来源: AIP