Corrections to the Asymptotic Holtsmark Formula for Hydrogen Lines Broadened by Electrons and Ions in a Plasma

Corrections to asymptotic Holtsmark formula for hydrogen lines broadened by electrons and ions in plasm

Electron Impact Broadening of Isolated Ion Lines

Electron impact broadening of isolated ion spectral line

Study of a colliding laser-produced plasma by analysis of time and space-resolved image spectra

The interaction of two counter-propagating laser-produced plasmas was studied using simultaneous imaging and spectroscopic techniques. Spectrally-filtered time-gated ICCD imaging was used to obtain information about the spatial dynamics and temporal evolution of the collision process. While, time-resolved imaging spectroscopy was used to determine the spatial and temporal distributions of electron temperature and density within the interaction region. We examine specifically the interaction of plasmas whose parameters match those typically used in pulsed laser deposition of thin films. These low temperature plasmas are highly collisional leading to the creation of a pronounced stagnation layer in the interaction region

Experimental and theoretical investigation of plasma radiation Semiannual status report, Sep. 1969 - Feb. 1970

Stark broadening of argon and neon resonance line

Experimental and theoretical investigation of plasma radiation Semi-annual status report, Mar. - Aug. 1969

Stark-broadened emission lines in plasma radiatio

Using Absorption Imaging to Study Ion Dynamics in an Ultracold Neutral Plasma

We report optical absorption imaging of ultracold neutral plasmas.Images are used to measure the ion absorption spectrum, which is Doppler-broadened. Through the spectral width, we monitor ion equilibration in the first 250ns after plasma formation. The equilibration leaves ions on the border between the weakly coupled gaseous and strongly coupled liquid states. On a longer timescale of microseconds, we observe radial acceleration of ions resulting from pressure exerted by the trapped electron gas.Comment: 4 pages, 4 figure

Dynamic and Stagnating Plasma Flow Leading to Magnetic Flux Tube Collimation

Highly collimated, plasma-filled magnetic flux tubes are frequently observed on galactic, stellar and laboratory scales. We propose that a single, universal magnetohydrodynamic pumping process explains why such collimated, plasma-filled magnetic flux tubes are ubiquitous. Experimental evidence from carefully diagnosed laboratory simulations of astrophysical jets confirms this assertion and is reported here. The magnetohydrodynamic process pumps plasma into a magnetic flux tube and the stagnation of the resulting flow causes this flux tube to become collimated.Comment: to be published in PRL; color figures on electronic versio

Microfield distributions in strongly coupled two-component plasmas

The electric microfield distribution at charged particles is studied for two-component electron-ion plasmas using molecular dynamics simulation and theoretical models. The particles are treated within classical statistical mechanics using an electron-ion Coulomb potential regularized at distances less than the de Broglie length to take into account the quantum-diffraction effects. The potential-of-mean-force (PMF) approximation is deduced from a canonical ensemble formulation. The resulting probability density of the electric microfield satisfies exactly the second-moment sum rule without the use of adjustable parameters. The correlation functions between the charged radiator and the plasma ions and electrons are calculated using molecular dynamics simulations and the hypernetted-chain approximation for a two-component plasma. It is shown that the agreement between the theoretical models for the microfield distributions and the simulations is quite good in general.Comment: 18 figures. Submitted to Phys. Rev.

Early-time measurements of laser-plasma conditions in OMEGA-upgrade ICF targets. Final report, April 1, 1998--January 31, 1999

All of the experimental results from OMEGA shots described here are from CY-1998 experiments under an (extended) FY-98 grant. This research involves fielding at LLE their two flat-field euv spectrographs in the 30--250 {angstrom} range, mainly utilizing on one o them a gated stripline microchannel plate as a time-resolved detector, with photographic recording. The experimental layout for the 1998 experiments is shown. During the week beginning May 3, 1998, the authors obtained 24 data shots over 4 days, and fielded both the time-gated extreme ultraviolet (euv) spectrograph mounted external to the target chamber, as well as their newly-constructed TIM-mounted euv spectrograph mounted closer to the target with time-integrated photographic recording on a trial basis. They also had available the LLE/LLNL streak x-ray spectrograph and x-ray imaging cameras. In this series, the first two shots appeared from the x-ray streak spectra to be normal in the sense that the spectral line emissions from the two coatings sequenced beginning with magnesium followed by aluminum as the coatings were vaporized. Unfortunately, on the following shots in this campaign it became increasingly apparent that conditions had changed radically, and later analyses showed that x-ray spectra lines from the deep aluminum undercoating appeared initially along with weak magnesium lines, indicating a premature vaporization of the magnesium heavier top layer. The second campaign in 1998 occurred during the week beginning October 18, 1998 and consisted of 21 data shots over two extended (12-hour) days following setup. For this series the authors again used their externally-mounted euv spectrography with time resolution and the x-ray streak spectrograph and imaging cameras. Much to their relief, it was immediately evident from the x-ray streak spectra obtained that significant ablation of the magnesium coatings by a (presumed) prepulse was not present, as it had been in the May campaign