Plasmas with solid-state density at temperatures of a few eV will be produced in the near future at GSI by high-energy heavy ions. To diagnose these plasmas, novel methods–based on hard X-ray diagnostics–have to be applied. An investigation of the hydrodynamic expansion of the target requires a space- and time-resolved measurement of the plasma density. The determination of the target density independently of its temperature is obtained by a special X-ray pinhole camera enabling a selective registration of the target K-shell emission in combination with space- and time-resolved beam intensity measurements.

The effect of multiple ionization on Kα spectra is investigated for aluminum targets irradiated by intense lithium beams. Multiple ionization cross sections have been calculated using a formulation incorporating single-electron ionization probability in the binomial distribution. In contrast to conventional binary-encounter approximation (BEA) theory, the single-electron ionization probabilities for each atomic shell have been calculated using a combination of modified plane-wave Born approximation (MPWBA) and an empirical effective interaction radius which is dependent on both the target ion and the projectile. Our calculations show that the effect of multiple inner-shell ionization on aluminum Kα spectra observed in intense lithium beam experiments is important. Multiple ionization effects become less important as the target ionization state increases. Nevertheless, even for highly ionized species up through Be-like Al multiple ionization effects can be significant and must be considered in the analysis of spectra obtained in intense Li beam-plasma interaction experiments.

Basic characteristics of an ablation plasma produced by an intense, pulsed, ion beam have been evaluated from the measurement of ion-flux density by a biased ion collector. The target mass loss is detected by the measurement of the weight of the target in the comparison before and after the shot. A one-dimensional hydrodynamic model is introduced with the assumption of a high-power, light-ion beam-driven expansion and the following adiabatic expansion into vacuum. With this model, it is possible for us to deduce the temperature and the pressure from the data of the ion flux and the mass loss of the target, respectively. This method is also applicable to other intense pulsed energy sources such as lasers or electron beams.

Correlated stopping of N ion debris flowing at same velocity in a lithium target is worked out from the Basbas-Ritchie model of 2-cluster stopping in degenerate electron jellium. A very large energy loss enhancement is demonstrated. It is strongly modulated by the ions' topological arrangement. Relevance to inertial fusion driven by intense cluster ion beam is stressed.

Focusing of heavy-ion beams is an important issue for ion beam-driven inertial confinement fusion. For the experimental program to investigate matter at high energy densities at GSI, the application of a plasma lens has attractive features compared to standard quadrupole lenses. A plasma lens using a wall-stabilized discharge has been systematically investigated and optimized for this purpose. Different lenses were tested in several runs at the GSI linear accelerator UNILAC and at the SIS-synchrotron. A remarkably high accuracy and reproducibility of the focusing were found. The focal spot size was mainly limited by the beam emittance. A summary of experimental results and important limitations of the focal spot size is given.

Kα satellite spectroscopy can be a valuable technique for diagnosing conditions in high energy density plasmas. Kα emission lines are produced in intense light ion beam plasma interaction experiments as 2p electrons fill partially open Is shells created by the ion beam. In this paper, we present results from collisional-radiative equilibrium (CRE) calculations which show how Kα emission spectroscopy can be used to determine target plasma conditions in intense lithium beam experiments on Particle Beam Fusion Accelerator-II (PBFAII) at Sandia National Laboratories. In these experiments, 8–10 MeV lithium beams with intensities of 1–2 TW/cm2 irradiate planar multilayer targets containing a thin Al tracer. Kα emission spectra are measured using an X-ray crystal spectrometer with a resolution of λ/∆λ = 1200. The spectra are analyzed using a CRE model in which multilevel (NL ∼ 103) statistical equilibrium equations are solved self-consistently with the radiation field and beam properties to determine atomic level populations. Atomic level-dependent fluorescence yields and ion-impact ionization cross sections are used in computing the emission spectra. We present results showing the sensitivity of the Kα emission spectrum to temperature and density of the Al tracer. We also discuss the dependence of measured spectra on the X-ray crystal spectral resolution, and how additional diagnostic information could be obtained using multiple tracers of similar atomic number.

An analytic model of ion beam driven hohlraums is presented which is used to determine the optimal hohlraum design parameters. It is shown that the radiation intensity within the hohlraum can exceed the average ion intensity driving the hohlraum. This “greenhouse effect” significantly lowers ion beam intensity requirements for driving a fusion microexplosion.

The Hartree-Fock theory of fluctuations leading to simple formulae for configuration probabilities is used in a Detailed Configuration Accounting calculation of opacity in the case of an iron plasma. A direct Detailed Term Accounting method is also applied. The correlations of subshell occupation numbers, which are accounted for in the HF theory, show small effect on the theoretical spectrum corresponding to conditions of a recent measurement.

The influence of discrepancies between analytical expressions for charge changing cross section on the ionization state of swift heavy ions interacting with hot and dense plasmas is analyzed within the framework of our new average correlated hydrogenic atom model. Making use of our Classical Trajectory Monte-Carlo results, we show that the partial charge transfer cross section into the projectile atomic levels has the same importance as the total charge transfer cross section.

A general and powerful formalism has been developed for computation of energy-loss spectra of penetrating charged particles in the presence of charge exchange. Options on the input side are the cross sections for electron capture and loss, transition rates for radiative and nonradiative spontaneous processes and their associated energy losses or gains, and finally, cross sections for all processes that contribute to particle stopping but are not associated with charge exchange. The formalism generates an n × n transfer matrix, where n is the number of states needed for an adequate description of the projectile under consideration. This matrix delivers the joint distribution of energy loss and exit charge state for a given incident charge state and energy.

The formalism can be used in principle as an alternative for Monte Carlo simulation, but until now we have concentrated on direct evaluation of key experimental parameters related to the energy-loss spectrum integrated over all exit charge states, in particular, mean energy loss, straggling, and skewness. Generally, valid analytic expressions have been found for these quantities, each of which can be separated into a stationary term representing chargestate equilibrium and a transient depending on the incident charge state. A brief survey is given of current analytic and numerical efforts addressing other experimental parameters.

Charge transfer of 4.3 MeV/u chlorine ions passing through a discharge plasma target is used as a probe to determine the plasma density and the ratio of impurities inside the plasma column. Charge-state distributions of 2 MeV/u chlorine ions passing through the plasma are then measured and compared to corresponding measurements in the cold gas. Stopping power measurements are also performed in both cases.

A density-matrix approach is under development for the investigation of the angular distribution and polarization of atomic radiative emissions in crossed quasi-static electric and magnetic fields. Particular interest has centered on applications to spectroscopic observations in the intense fields of the high-power light-ion inertial fusion device PBFA II at Sandia National Laboratories, and to magnetic field measurements in tokamak plasmas. Noteworthy features of our general density-matrix analysis include allowances for the mixing of both the bound and continuum field-free atomic eigenstates in an arbitrary arrangement of electric and magnetic fields, and for the possible coherent excitation of the nearly degenerate field-dependent atomic substates that produce the overlapping Stark-Zeeman components. The influence of directed collisional excitation may also be taken into account. From the angular-momentum selection rules, specific results have been obtained for observation of polarized radiative emissions in the direction of the magnetic field.

We investigate the stopping power of heavy ions in strongly coupled electron plasmas by performing molecular dynamics (MD) computer simulations. A comparison with conventional weak coupling theories shows that these fail in describing the stopping power at low ion velocities and strong coupling. Then nonlinear screening effects become important and this causes a change in the dependence of the stopping power on the ion charge Zp at low ion velocities. From the MD simulation, we find the stopping power to behave like ZP1.43 instead of the weak coupling behavior Zp2 ln(const/Zp). Similar results were recently obtained by experiments in connection with electron cooling at heavy ion storage rings.

In Chapter 14 of Atomic and Molecular Processes, Bates (1962) outlines a procedure for calculating ion-atom cross sections in the plane-wave Born approximation (pwBa). The procedure involves integration over the product of elastic scattering factors or generalized oscillator strengths for excitation or ionization from both projectile and target. We have programmed this procedure to use our large database of excitation and ionization generalized oscillator strengths (GOS). The program calculates both cross sections (CS) and stopping power (SP) on a subshell basis. The calculations are done in the center of mass system where the distinction between projectile and target is lost. Thus, the SP in the laboratory frames of both target and projectile are symmetrical in nuclear and net charges. The traditional simple modeling of SP, using scaled proton SP and an effective projectile charge, is unsymmetrical, and therefore dubious as a guide for extrapolating to ion-ion SP. At high projectile energy, the SP curves, as a function of increasing projectile charge, approach the scaled protonic result from above, indicating that lowering the average charge raises the SP, in contradiction to the traditional picture that the projectile SP increases with increasing effective charge (assuming there is an underlying physical reality relating the effective and average charge). Comparison with experimental SP data (mostly from 30 years ago) shows generally poor agreement for Li ion projectiles in the 1–10 MeV range.

The energy loss and disintegration dynamics of large carbon clusters (C60 molecules) in hot plasmas is calculated. The calculation self-consistently includes the cluster disintegration, the evolution of the charge of the fragment ions, the screened Coulomb forces among them, and the effects of interference between neighboring ions on the energy loss. A range of projectile energies and plasma parameters is considered. A large enhancement factor in the energy deposition due to the interference is found at the early stage of the interaction.

A new type of ion-beam diode, self-magnetically insulated, spherical plasma focus diode (SPFD), was developed. With the SPFD, three-dimensional focusing of an intense pulsed light-ion beam was obtained. Experiments and simulations were carried out to study the behavior of the SPFD. In the experiments, diagnostic results of the Rutherford scattering pinhole camera and the shadow-box showed that the ion beam was focused into a small cylindrical area with ∽0.5 mm in diameter and ∽2.5 mm in length. The average ion-beam current density at the anode surface was found to be ∽2 kA/cm2. In the simulations, it was observed that most of the diode gap is well insulated by the self-magnetic field induced by the diode current. The electron sheath in the diode gap significantly enhances the ion flow from the anode. As a result, the ion current density is several times higher than the single-species space-charge limited value.