High-resolution Thomson parabola for ion analysis.

A new, versatile Thomson parabola ion energy (TPIE) analyzer has been designed, constructed, and used at the OMEGA-EP facility. Laser-accelerated multi-MeV ions from hemispherical C targets are transmitted through a W pinhole into a multi-kG magnetic field and subsequently through a parallel electric field of up to 25 kV/cm. The ion drift region has a user-selected length of 10, 50, or 80 cm.

High-power, kilojoule class laser channeling in millimeter-scale underdense plasma.

Experiments were performed using the Omega EP laser, operating at 740 J of energy in 8 ps (90 TW), which provides extreme conditions relevant to fast ignition studies. A carbon and hydrogen plasma plume was used as the underdense target and the interaction of the laser pulse propagating and channeling through the plasma was imaged using proton radiography. The early time expansion, channel evolution, filamentation, and self-correction of the channel was measured on a single shot via this method.

Phase-contrast imaging using ultrafast x-rays in laser-shocked materials.

High-energy x-rays, >10 keV, can be efficiently produced from ultrafast laser target interactions with many applications to dense target materials in inertial confinement fusion and high-energy density physics. These same x-rays can also be applied to measurements of low-density materials inside high-density Hohlraum environments. In the experiments presented, high-energy x-ray images of laser-shocked polystyrene are produced through phase contrast imaging.

A high-temperature high-pressure calorimeter for determining heats of solution up to 623 K.

A high-temperature high-pressure isoperibol calorimeter for determining the heats of solution and reaction of very dilute substances in water (10(-4) m) at temperatures up to 623 K is described. The energies of vaporization of water at steam saturation pressure were measured as a function of temperature and the results agree with the corresponding values from steam tables to better than 0.08+/-0.

Thermodynamic properties of aqueous polyatomic ions at extreme temperatures and pressures.

Recently a theoretical treatment (J. Phys. Chem.

Standard state thermodynamic properties of completely ionized aqueous sodium sulfate using high dilution calorimetry up to 598.15 K.

Pabalan and Pitzer (Geochim. Cosmochim. Acta 1988, 52, 2393-2404) reported a comprehensive set of thermodynamic properties of aqueous solutions of sodium sulfate without using ion association or hydrolysis.

Standard state thermodynamic properties of completely dissociated hydrochloric acid and aqueous sodium hydroxide at extreme temperatures and pressures.

Standard state thermodynamic properties for completely dissociated hydrochloric acid were fixed by ionic additivity, using the data from other strong electrolytes perrhenic acid, sodium perrhenate, and sodium chloride from 298.15 to 598.15 K and at p(sat).

Standard state thermodynamic properties of aqueous sodium chloride using high dilution calorimetry at extreme temperatures and pressures.

In this communication, we report the first calorimetric data for the standard state enthalpies of a solution of sodium chloride obtained from high dilution, down to (10(-3) m), integral heats of solution measurements to 596.30 K. Although there are no comparable thermodynamic data available at such high dilutions in the literature, the present results for NaCl(aq) can be used for many thermodynamic studies by others to achieve a complete thermodynamic description of this key electrolyte over very wide ranges of concentration.

A unified theory of the thermodynamic properties of aqueous electrolytes to extreme temperatures and pressures.

A new theoretical treatment has been developed for predicting the thermodynamic properties of electrolytes up to and beyond the critical temperature of water (973 K and at pressures up to 1000 MPa). The model is based upon the classical Born equation corrected for non-Born hydration effects. The temperature and pressure behavior of electrolytes can now be accurately predicted from existing low temperature data.

Standard state thermodynamic properties of Ba2+(aq), Co2+(aq), and Cu2+(aq) up to 598.15 K, and temperature effect on ligand field.

Integral heat of solution measurements of barium chloride to 619.81 K, copper oxide in an excess of perrhenic acid to 585 K, and cobalt perrhenate in perrhenic acid to 573 K were measured in a high dilution calorimeter (< or =10(-3) m) at psat, from which the high temperature thermodynamic properties of aqueous barium chloride, copper perrhenate, and cobalt perrhenate were obtained. From the known differences between the corresponding properties for aqueous perrhenate and chloride ions, the thermodynamic properties of completely ionized aqueous copper and cobalt chloride were obtained from ionic additivity.

Thermodynamic properties of aqueous gadolinium perrhenate and gadolinium chloride from high dilution calorimetry at extreme temperatures and pressures.

The heat of solution of solid cubic gadolinium oxide has been measured in noncomplexing perrhenic acid solutions at very high dilutions (10(-4) m) up to 596.30 K, from which the standard state thermodynamic properties of aqueous gadolinium perrhenate were determined up to 623.15 K.

TRIDENT high-energy-density facility experimental capabilities and diagnostics.

The newly upgraded TRIDENT high-energy-density (HED) facility provides high-energy short-pulse laser-matter interactions with powers in excess of 200 TW and energies greater than 120 J. In addition, TRIDENT retains two long-pulse (nanoseconds to microseconds) beams that are available for simultaneous use in either the same experiment or a separate one. The facility's flexibility is enhanced by the presence of two separate target chambers with a third undergoing commissioning.

High-energy, high-resolution x-ray imaging on the Trident short-pulse laser facility.

With the completion of the Trident laser facility upgrade, 200 TW high-energy laser pulses are now capable of producing x-ray pulses with energies in the range of 15-40 keV, which will be used for high-spatial resolution radiography. A diagnostic suite is being developed on the laser system to investigate and characterize the x-ray emission from high-Z targets. This includes charge coupled device based single-photon counters, imaging plates, a high-energy electronic imager, spectral diagnostics, and optical and x-ray spot size diagnostics.

Analytical model for ion acceleration by high-intensity laser pulses.

We present a general expression for the maximum ion energy observed in experiments with thin foils irradiated by high-intensity laser pulses. The analytical model is based on a radially confined surface charge set up by laser accelerated electrons on the target rear side. The only input parameters are the properties of the laser pulse and the target thickness.

Transverse characteristics of short-pulse laser-produced ion beams: a study of the acceleration dynamics.

We report on first measurements of the transverse characteristics of laser-produced energetic ion beams in direct comparison to results for laser accelerated proton beams. The experiments show the same low emittance for ion beams as already found for protons. Additionally, we demonstrate that the divergence is influenced by the charge over mass ratio of the accelerated species.

Laser acceleration of quasi-monoenergetic MeV ion beams.

Acceleration of particles by intense laser-plasma interactions represents a rapidly evolving field of interest, as highlighted by the recent demonstration of laser-driven relativistic beams of monoenergetic electrons. Ultrahigh-intensity lasers can produce accelerating fields of 10 TV m(-1) (1 TV = 10(12) V), surpassing those in conventional accelerators by six orders of magnitude. Laser-driven ions with energies of several MeV per nucleon have also been produced.

Observation of a transition from fluid to kinetic nonlinearities for langmuir waves driven by stimulated Raman backscatter.

Thomson scattering is used to measure Langmuir waves (LW) driven by stimulated Raman scattering (SRS) in a diffraction limited laser focal spot. For SRS at wave numbers klambda(D) less similar 0.29, where k is the LW number and lambda(D) is the Debye length, multiple waves are detected and are attributed to the Langmuir decay instability (LDI) driven by the primary LW.

Comparison of laser ion acceleration from the front and rear surfaces of thin foils.

The comparative efficiency and beam characteristics of high-energy ions generated by high-intensity short-pulse lasers (approximately 1-6 x 10(19) W/cm2) from both the front and rear surfaces of thin metal foils have been measured under identical conditions. Using direct beam measurements and nuclear activation techniques, we find that rear-surface acceleration produces higher energy particles with smaller divergence and a higher efficiency than front-surface acceleration. Our observations are well reproduced by realistic particle-in-cell simulations, and we predict optimal criteria for future applications.

Ultralow emittance, multi-MeV proton beams from a laser virtual-cathode plasma accelerator.

The laminarity of high-current multi-MeV proton beams produced by irradiating thin metallic foils with ultraintense lasers has been measured. For proton energies >10 MeV, the transverse and longitudinal emittance are, respectively, <0.004 mm mrad and <10(-4) eV s, i.

Charge-exchange-induced two-electron satellite transitions from autoionizing levels in dense plasmas.

Order-of-magnitude anomalously high intensities for two-electron (dielectronic) satellite transitions, originating from the He-like 2s(2) 1S0 and Li-like 1s2s(2) (2)S(1/2) autoionizing states of silicon, have been observed in dense laser-produced plasmas at different laboratories. Spatially resolved, high-resolution spectra and plasma images show that these effects are correlated with an intense emission of the He-like 1s3p 1P-1s(2) 1S lines, as well as the K(alpha) lines. A time-dependent, collisional-radiative model, allowing for non-Maxwellian electron-energy distributions, has been developed for the determination of the relevant nonequilibrium level populations of the silicon ions, and a detailed analysis of the experimental data has been carried out.

Hot, dense, millimeter-scale, high-Z plasmas for laser-plasma interactions studies.

We have designed and produced hot, millimeter-scale, high-Z plasmas of interest for National Ignition Facility hohlraum target design. Using a high-Z gas fill produces electron temperatures in the 3.5-6-keV range, the highest temperatures measured to date for high-density (10(21) e/cm(3)) laser-heated plasmas, and much higher than the 3 keV found for low-Z (neopentane) fills.

Observation of stimulated electron-acoustic-wave scattering.

A diffraction-limited laser interacts with a plasma whose conditions are uniform on the scale of the focused laser spot. Two distinct, narrow waves are observed in the backscattered spectrum with phase velocities of v(phi)/v(e) = 1.4+/-0.