Low-frequency component e l e c t r i c m i c r o f i e l d d i s t r i b u t i o n s i n a plasmaa r e c a l c u l a t e d a t b o t h a n e u t r a l and charged p o i n t . ' I t is shown t h a t t h i s c a l c u l a t i o n a l l o w s f o r t h e i n c l u s i o n of a l l c o r r e l a t i o n s t o a h i g h degree of accuracy. A d e t a i l e d a n a l y s i s of a l l approximations i s i n c l u d e d , t o g e t h e r w i t h a "lonteThe t h e o r y i s compared w i t h t h e Holtsmark and Baranger-Mozer t h e o r i e s . C a r l o s t u d y . Numerical r e s u l t s a r e shown both g r a p h i c a l l y and i n t a b u l a t e d f o m .

A new method for calculating the distribution oi electric microfields (high-frequency components) in a plasma is developed. Distributions are calculated at both a neutral and a charged point. The plasma is taken to be a system of X charged particles moving in a uniform neutralizing background. It is shown that this development allows for the inclusion of all correlations to a high degree of accuracy. This theory is then compared with the Holtsmark and Baranger-Mozer theories. A detailed analysis of all approximations is included, together with a Monte Carlo study. Numerical results are shown both graphically and in tabulated form.

Direct-drive-implosion core conditions have been characterized on the 60-beam OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] laser system with time-resolved Ar K-shell spectroscopy. Plastic shells with an Ar-doped deuterium fill gas were driven with a 23 kJ, 1 ns square laser pulse smoothed with 1 THz smoothing by spectral dispersion (SSD) and polarization smoothing (PS) using birefringent wedges. The targets are predicted to have a convergence ratio of ∼15. The emissivity-averaged core electron temperature (Te) and density (ne) were inferred from the measured time-dependent Ar K-shell spectral line shapes. As the imploding shell decelerates the observed Te and ne increase to 2.0 (±0.2) keV and 2.5 (±0.5)×1024 cm−3 at peak neutron production, which is assumed to occur at the time of the peak emissivity-averaged Te. At peak compression the ne increases to 3.1 (±0.6)×1024 cm−3 and the Te decreases to 1.7 (±0.17) keV. The observed core conditions are close to those predicted by a one-dimensional hydrodynamics code.

A theoretical formalism and computer code have been developed to calculate spectra of multielectron emitters in plasmas. The plasma electron broadening is treated by a quantum-mechanical relaxation theory. The static-ion approximation is used to treat plasma ion broadening of the atomic levels. Calculated lithiumlike and berylliumlike krypton spectra are compared to experimental spectra obtained in laser implosion experiments at the Laboratory for Laser Energetics, University of Rochester.

GAS PUMPING IN Ar DISCHARGEdependence of hp/L on M may be more complicated than Eq. (A1) indicates. Equation (A9) predicts hp/L ccI/p, just as Ruttenauer observed, but unfortunately the use of the highpressure form for Vs in Eq. (A8) Lwhich leads to Eq. (A9) ] cannot be justiled in the case of helium and.neon. The critical value of pR separating the highpressure and low-pressure forms for V3 may be written pR=1.06V, (p in Torr, R in mm, V, in V) in argon. However, according to Francis, V, ranges from 5 to 15 V for helium and neon in Ruttenauer's experimen. ts. (Such high electron temperatures have been observed by Labuda and Gordons' in helium-neon discharges. ) Physically, this then means that the radial 6elds are much greater in helium and. neon than in argon at similar values of pR, so that ion radial drift velocities are considerably greater in the lighter gases at a given value of pR.Thus V3 will still have its "small x" form at some values of pR in argon but its "large x" form at the same values of pR in neon or helium. (1964).should occur at pR=2.02V, in neon pR=2. 22V, in, helium (p in, Torr, R in mm, V, in V). If the high values of electron temperature previously mentioned occurred in Ruttenauer's tubes, then it is clear that the appropriate form for Vs in Eq. (A"/) should be the low pressure form (the large-x limit). As previously remarked in the case of argon, the large-x limit of V~is pressure-independent, so that the 1/p dependence found by Ruttenauer cannot be accounted for in this case.The resolution of this remaining disagreement must await further work. Perhaps the electron temperature in Ruttenauer's range of current and pressures is lower than estimated here, in which case Eq. (A9) would still be applicable and would account for his measurements in helium and neon. Perhaps other pumping processes at work in these gases make Va an incomplete description of the pumping mechanism. Or perhaps, because of the small currents used by Ruttenauer, changes in electron temperature and axial field as a function of current obscured a true interpretation of the pressure dependence over the limited range of parameters he used in his work on helium and neon.A recently developed collective-coordinate technique is employed to calculate electric micro6eld distribution functions P(e) for low-frequency-component plasmas. Values of e considered range from 10 to 50, and both neutral-point and charged-point cases are treated. Comparison is made with appropriate asymptotic expressions.