Stamm et al. Respond: The critical Comment byApruzese et al l does not seem to give convincing arguments against the existence of a strong iondynamical effect in inertial-confinement-fusion conditions. The observation of Lyman-/3 (L^) dips in laser-driven pellet implosions (their Refs. 2-6) is not in contradiction with our first calculation of L^ for hydrogenic argon perturbed by protons for N e = 1.5 x 10 23 cm -3 and r e = 10 7 K. Indeed, the effect of ion dynamics strongly depends 2 on the choice of Z e , Z p , N e9 T e , and M . For A^ = 4xl0 23 cm" 3 , T e = 800 eV, Z p = 1 (deuteron perturbers), we have recently used our model to obtain a hydrogenic argon L^ profile displaying a distinct dip in the center of the line. 3 This calculation (corresponding to Ref. 5 of the Comment) demonstrates that the observation of a dip on L^ strongly depends on the physical parameters of the experiment. On the other hand, our L a , L^, and L y line profiles for these conditions are still very different, in their central part, from the profiles which use static ions. This indicates that it is possible to observe a strong influence of ion dynamics even when a dip is observed on L^.

A computer simulation has been applied to the calculation of Stark profiles of hydrogenic ions for the conditions of inertial confinement fusion. Drastic modifications of the Lymanline profiles are observed when ion dynamics is taken into account.PACS numbers: 32.70.Jz, 32.30.Rj, 32.60.+i In most of the early Stark broadening theories, it was assumed that the plasma ions could be treated as stationary during the radiative lifetime of an excited atom or ion in the plasma. However, in recent years it has been shown both experimentally 1 and theoretically 2 " 5 that the motion of these ions can produce significant alterations near line center, particularly for low-lying series members 6 such as Lyman-a (L a ) and Lyman-/3 (L^). For a plasma density of N e =l0 17 cm"" 3 , this so-called "ion dynamics" effect can change the halfwidth by a factor of 2. 6 Since all current tabulations of Stark profiles for hydrogen 7 or hydrogenic ions 8 have employed the static-ion approximation, the use of L a and Lp from these tables could result in serious errors in density diagnostics. The situation becomes especially unsatisfactory for the hot, dense plasmas encountered in inertial confinement fusion (ICF), because the density diagnostics rely heavily on fitting the experimental profiles with the theoretical profiles of hydrogenic ions. 9 ' 10 Attempts have been made recently by Cauble and Griem 11 to include the effect of ion dynamics in an approximate way for the Lyman lines of Arxvm broadened by deuterium-tritium (DT) plasmas. For a density N e = 5 x 10 23 cm" 3 and a temperature T e = 4.6 x 10 6 K, they found roughly a doubling in the halfwidth of L a . In the present work, we use a computer simulation to demonstrate that in ICF conditions, the introduction of ion dynamics has a much larger effect on the profile, producing an order of magnitude increase in the halfwidth of L a .Our computer simulation for the ions in the plasma is based on a model of statistically independent quasiparticles moving in a spherical box, 5, n and interacting with the radiator through a Debye shielded field, T,-(Z,

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