In this article, we analyze the sensitivity of the charge and energy distribution of a swift heavy ion beam interacting with a dense plasma on the thermodynamic and dynamic properties of the target. We study more particularly partially ionized carbon targets in which both the bound and the free electrons yield a significant contribution to the stopping. The emphasis is put on direct and indirect correlation between charge transfer and stopping. We show that nonlinearities, appearing in the interaction process for heavy ions, increase the dependency of the stopping on the plasma properties, indicating that diagnostics based on the analysis of the beam ions can provide valuable information on the target properties.

A model for the stopping power for strong beam–plasma coupling is presented. The model calculates the stopping power through a T-matrix approach which correctly describes close binary collisions. A velocity-dependent screening length is used in the beam particle–plasma electron interaction to include dynamic screening effects. The model has the correct limiting behavior for low and high beam particle velocities and agrees well with simulation data up to very high coupling strengths. Compared to other theories, which include strong correlations and/or dynamic screening only approximately, a smaller energy loss has been found; this leads to a considerably longer stopping range.

The charge-state distribution and the energy loss of oxygen ions in a laser-produced hydrogen plasma have been investigated experimentally. The plasma target had a maximum electron density of 5 × 1018 cm−3 and a maximum electron temperature of 13 eV. The mean charge state of the oxygen ions in the hydrogen plasma was measured to be 5.1, which was considerably higher than that in hydrogen gas. The energy loss of oxygen ions in the plasma of a density less than 1 × 1018 cm−3 in the plasma showed a large enhancement compared with that in hydrogen gas. However, the energy loss in the plasma of a density above 1 × 1018 cm−3 showed no enhancement.

The X-ray spectral distribution of swift heavy Ti and Ni ions (11 MeV/u) observed inside aerogels (ρ = 0.1 g/cm3) and dense solids (quartz, ρ = 2.23 g/cm3) indicates a strong presence of simultaneous 3–5 charge states with one K-hole. We show that the theoretical analysis can be split into two tasks: first, the treatment of complex autoionizing states together with the originating spectral distribution, and, second, a charge-state distribution model. Involving the generalized line profile function theory, we discuss attempts to couple charge-state distributions.

At the Gesellschaft für Schwerionenforschung (GSI, Darmstadt) intense beams of energetic heavy ions have been used to generate high-energy-density (HED) state in matter by impact on solid targets. Recently, we have developed a new method by which we use the same heavy ion beam that heats the target to provide information about the physical state of the interior of the target (Varentsov et al., 2001). This is accomplished by measuring the energy loss dynamics (ELD) of the beam emerging from the back surface of the target. For this purpose, a new time-resolving energy loss spectrometer (scintillating Bragg-peak (SBP) spectrometer) has been developed. In our experiments we have measured energy loss dynamics of intense beams of 238U, 86Kr, 40Ar, and 18O ions during the interaction with solid rare-gas targets, such as solid Ne and solid Xe. We observed continuous reduction in the energy loss during the interaction time due to rapid hydrodynamic response of the ion-beam-heated target matter. These are the first measurements of this kind. Two-dimensional hydrodynamic simulations were carried out using the beam and target parameters of the experiments. The conducted research has established that the ELD measurement technique is an excellent diagnostic method for HED matter. It specifically allows for direct and quantitative comparison with the results of hydrodynamic simulations, providing experimental data for verification of computer codes and underlying theoretical models. The ELD measurements will be used as a standard diagnostics in the future experiments on investigation of the HED matter induced by intense heavy ion beams, such as the HI-HEX (Heavy Ion Heating and EXpansion) EOS studies (Hoffmann et al., 2002).

In heavy ion fusion, the compression of the DT pellet requires high intensity beams of ions in the gigaelectron volt energy range. Charge-changing collisions due to intrabeam scattering can have a high impact on the design of adequate accelerator and storage rings. Not only do intensity losses have to be taken into account, but also the deposition of energy on the beam lines after bending magnets, for example, may be nonnegligible. The center-of-mass energy for these intrabeam collisions is typically in the kiloelectron volt range for beam energies in the order of several gigaelectron volts. In this article, we present experimental cross sections for charge transfer and ionization in homonuclear collisions of Ar4+, Kr4+, and Xe4+, and for charge transfer only in homonuclear collisions of Pb4+ and Bi4+. Using a hypothetical 100-Tm synchrotron as an example, expected particle losses are calculated based on the experimental data. The results are compared with expectations for singly charged Bi+ ions, which are usually considered for heavy ion fusion.

The propagation of a high-current finite-length ion charge bunch through a background plasma is of interest for many applications, including heavy ion fusion, plasma lenses, cosmic ray propagation, and so forth. Charge neutralization has been studied both analytically and numerically during ion beam entry, propagation, and exit from the plasma. A suite of codes has been developed for calculating the degree of charge and current neutralization of the ion beam pulse by the background plasma. The code suite consists of two different codes: a fully electromagnetic, relativistic particle-in-cell code, and a relativistic Darwin model for long beams. As a result of a number of simplifications, the second code is hundreds of times faster than the first one and can be used for most cases of practical interest, while the first code provides important benchmarking for the second. An analytical theory has been developed using the assumption of long charge bunches and conservation of generalized vorticity. The model predicts nearly complete charge neutralization during quasi-steady-state propagation provided the beam pulse duration τb is much longer than the inverse electron plasma frequency ωp−1, where ωp = (4πnp e2/me)1/2 and np is the background plasma density. In the opposite limit, the beam head excites large-amplitude plasma waves. Similarly, the beam current is well neutralized provided ωpτb >> 1 and the beam radius is much larger than plasma skin depth δp = c/ωp. Equivalently, the condition for current neutralization can be expressed in terms of the beam current as Ib >> 4.25Zb βb(nb /np)kA, where nb is the beam density, Zb is the ion charge, and Vb = βb c is the beam velocity; and the condition for charge neutralization can be expressed as Ib >> 4.25βb3(nb /np)(rb /lb)2kA, where lb and rb are the beam length and radius, respectively. For long charge bunches, the analytical results agree well with the results of numerical simulations. The visualization of the data obtained in the numerical simulations shows complex collective phenomena during beam entry into and exit from the plasma.

Discharge plasma channels have been investigated in recent years at Gesellschaft für Schwerionenforschung–Darmstadt (GSI) and at the Lawrence Berkeley National Laboratory in Berkeley, California, in a number of experiments. A short summary of the experimental work at Berkeley and GSI is given. Different initiation mechanisms for gas discharges of up to 60 kA were studied and compared. In the Berkeley experiments, laser ionization of organic vapors in a buffer gas was used to initiate and direct the discharge while at GSI, laser gas heating and ion-beam-induced gas ionization were tested as initiation mechanisms. These three initiation techniques are compared and the stability of the resulting discharge channels is discussed. A discharge current of 50 kA, a channel diameter well below 1 cm, a pointing stability better than 200 μm, and MHD stability of more than 10 μs have been demonstrated simultaneously in the recent experiments. These parameters are sufficient or close to the requirements of a reactor application depending on the details of the target design. The experimental results show that transport channels work with sufficient stability, reproducibility, and ion optical properties for a wide pressure range of discharge gases and pressures.

The experimental results of the activation spectra, dose rate measurements, and the residual nuclide production cross sections obtained after the irradiation of the NatCu and 59Co targets by 12C ion beams at ITEP and GSI are presented in this paper. These results are compared with simulations by the CASCADE and LAQGSM codes.

The Target Fabrication Facility (TFF) of an inertial fusion energy (IFE) power plant must supply about 500,000 targets per day. The target is injected into the target chamber at a rate of 5–10 Hz and tracked precisely so the heavy ion driver beams can be directed to the target. The feasibility of developing successful fabrication and injection methodologies at the low cost required for energy production (about $0.25/target, approximately 104 times less than current costs) is a critical issue for inertial fusion energy. A significant program is underway to develop the high-volume methods to supply economical IFE targets. This article reviews the requirements for heavy ion driven IFE target fabrication and injection, and presents the current status of and results from the development program. For the first time, an entire pathway from beginning to end is outlined for fabrication of a high-gain, distributed radiator target. A significant development and scale-up program will be necessary to implement this pathway for mass production of IFE targets.

The dynamics of low entropy weak shock waves induced by heavy ion beams in solid targets was investigated by means of a schlieren technique. The targets consist of a metallic absorber for the beam energy deposition followed by a plexiglass block for optical observations. Multiple waves propagating with supersonic velocities at 15 kbar pressures were observed in the plexiglass, for pressures of up to 70 kbar numerically calculated in the absorbers. Pressures in the megabar ranges are predicted for a near future beam upgrade, enabling studies of phase transition to metallic states of H, Kr, and Xe.

The construction of short pulse (<200 fs) tunable X-ray laser sources based on the X-ray free electron laser (XFEL) concept will be a watershed for plasma-based and warm dense matter research. These new fourth generation light sources will have extremely high fields and short wavelengths (∼0.1 nm) with peak spectral brightnesses 1010 greater than third generation sources. Further, the high intensity upgrade of the GSI accelerator facilities will lead to specific energy depositions up to 200 kJ/g and temperatures between 1 and 10 eV at almost solid-state densities, enabling interesting experiments in the regime of nonideal plasmas, such as the evolution of intense ion beams in the interior of a Jovian planet. Below we discuss several applications: the creation of warm dense matter (WDM) research, probing of near solid density plasmas, and laser–plasma spectroscopy of ions in plasmas. The study of dense plasmas has been severely hampered by the fact that laser-based methods have been unavailable and these new fourth generation sources will remove these restrictions.

A hybrid configuration of a heat-capacity laser (HCL) and a moving-slab laser (MSL) is proposed. Multiple volumes of solid-state laser material are sequentially diode-pumped and their energy extracted. When a volume reaches a maximum temperature after a “submagazine depth,” it is moved out of the pumping region into a cooling region, and a new volume is introduced. The total magazine depth equals the submagazine depth times the number of volumes. The design parameters are chosen to provide high duty factor operation, resulting in effective use of the diode arrays. The concept significantly reduces diode array cost and is considered enabling for many potential applications.

The interaction of intense laser light with molecules and clusters is a rapidly evolving research area. Its attraction lies in both the underlying fundamental physics and the prospects for applications. The interaction of intense laser light with rare-gas clusters, for instance, leads to megaelectron volt electrons, multikiloelectron volt ions, and bright X-ray emission. In laser-irradiated D2 clusters, thermonuclear fusion has been achieved.