The interaction of nanoscale NaCl particles with 193-nm photons is studied to better understand particle disintegration and production by ultraviolet photofragmentation. The particles are irradiated in a constrained air stream with laser fluences from 0.08 to 0.23 J /cm2 with single and multiple pulses striking the particles. The resulting particle size distributions are measured with a scannin...

Laser interaction with nanoscale particles is distinct and different from laser-bulk material interaction, where a hot plasma is normally created. Here, we review our studies on 193 nm laser ablation of various nanoscale particles including NaCl, soot, polystyrene, and gold. The 20 ns laser beam with fluences up to 0.3 J/cm irradiates nanoparticles in a gas stream at laser repetition rates from...

Deposition process for thin insulator used in polysilicon gate dielectric of thin film transistors are optimized. Silane and N2O plasma are used to form SiO2 layers at temperatures below 150 ºC. The deposition conditions as well as system operating parameters such as pressure, temperature, gas flow ratios, total flow rate and plasma power are also studied and their effects are discussed.  The p...

We use a boost-invariant one-dimensional (cylindrically symmetric) fluid dynamics code to calculate thermal photon production in the central rapidity region of S+Au and Pb+Pb collisions at SPS energy ( √ s = 20 GeV/nucleon). We assume that the hot matter is in thermal equilibrium throughout the expansion, but consider deviations from chemical equilibrium in the high temperature (deconfined) pha...

We present coefficients for the calculation of the continuous emission spectra of H I, He I and He II due to electron-ion recombination. Coefficients are given for photon energies from the first ionization threshold for each ion to the n = 20 threshold of hydrogen (36.5μ), and for temperatures 100 K ≤ T ≤ 10 K. The emission coefficients for He I are derived from accurate ab initio photoionizati...

A two-photon laser-induced fluorescence study on the transport of ground-state atomic hydrogen in a supersonic plasma jet, generated from an Ar-H (2) mixture, reveals an unexpected shock pattern. Whereas both the axial-velocity profile and the temperature profile of hydrogen atoms along the jet centerline can be interpreted in terms of a supersonic expansion of an Ar-H gas mixture, the H-atom d...

Currently, the only known way to obtain experimental information about the space-time structure of a heavy-ion collision is through two-particle momentum correlations. Azimuthally sensitive Hanbury-Brown–Twiss (HBT) intensity interferometry can complement elliptic flow measurements by constraining the spatial deformation of the source and its time evolution. Performing these measurements on pho...

Surface and structural damage to plasma-facing components (PFCs) due to the frequent loss of plasma con®nement is a serious problem for the tokamak reactor concept. The plasma energy deposited on these components during loss of con®nement causes signi®cant surface erosion, possible structural failure, and frequent plasma contamination. Surface damage consists of vaporization, spallation, and li...

Photoionization has been a highly selective method for the preparation of polyatomic molecular ions [1]. VUV light, usually of low intensity, must be employed; the produced ion flux has, however, often been insufficient for many interesting appli­ cations. Classical methods have employed discharge lamps or, more recently, synchrotron radiation [2]. The former is limited to a few wavelengths a t...

The approach of a parton plasma at future heavy ion colliders towards kinetic and chemical equilibrium is considered. A plasma with a self-consistent evolving parton-parton interaction strength is shown to equilibrate better and faster than the usual but inconsistent one with a fixed strength. We explain why as a consequence of this, a parton plasma is a unique kind of many-body system. Because...