Research on multiply-ionized atoms was pioneered in the 1930s and 40s, particularly in Sweden by Edlén and his colleagues working first in M. Siegbahn's laboratory in Uppsala, and then at Lund University. The key instrument was the grazing-incidence grating spectrometer which opened to observation the spectral range 500–5Å (Edlén 1963). The source of the multiply-charged ions was the plasma of a vacuum spark, a pulsed (~1 µs) electric discharge of up to 50 kA between electrodes of the desired element, some 3–5 mm apart. When the spark was enclosed in a ceramic tube (with a side opening to let out the radiation), the breakdown voltage was less, the discharge was more controllable. Furthermore, it was found that the range of species produced was a useful function of current.

This paper describes the first results of a feasibility study undertaken at CERN to determine whether a laser-produced plasma can be used as a source of intense highly charged heavy ion beams. A variety of important measurements have been made, and the results are encouraging. Furthermore, a beam of highly charged light ions produced by the laser ion source has been accelerated successfully in a radio frequency quadrupole (RFQ) structure.

This paper presents a set of complementary corpuscular diagnostics applied in experiments for investigation of laser-produced plasma as a source of ions. The measuring possibilities and methods for processing experimental data of a cylindrical electrostatic ion energy analyzer, a Thomson parabola ion analyzer, various types of electrostatic probes, a detector of neutral atom fluxes, as well as methods for visualization of ion emission areas are discussed. Special attention was focused on the ion-induced secondary electron emission problem and its influence on the accuracy of the measurements.

The problem of matching an ion beam delivered by a high-intensity ion source with an accelerator is considered. The experimental results of highly charged ion beam transport with space-charge compensation by electrons are presented. A tungsten thermionic cathode is used as a source of electrons for beam compensation. An increase of ion beam current density by a factor of 25 is obtained as a result of space-charge compensation at a distance of 3 m from the extraction system. The process of ion beam space-charge compensation, requirements for a source of electrons, and the influence of recombination losses in a spacecharge-compensated ion beam are discussed.

Results are presented of experiments on ion production from Ta targets using a short pulse (350–600 ps in focus) illumination with focal power densities exceeding 1014 Wcm-2 at the wavelength of an iodine photodissociation laser (1.315 μm) and its harmonics. Strong evidence of the existence of tantalum ions with the charge state +45 near the target surface was obtained by X-ray spectroscopy methods. The particle diagnostics point to the existence of frozen high charge states (<53+) of Ta ions in the far expansion zone at about 2 m from the target. The measured charge state-ion energy distribution indicates the highest energy (>4 MeV) for the highest observed charge states. A tentative theoretical explanation of the observed anomalous charge state freezing phenomenon in the expanding plasma produced by a subnanosecond laser pulse is given.

The results of lead ion generation with charge state from Pb10+ to Pb35+ from laser-heated plasma are presented. CO2 lasers producing 10.6-μm wavelength radiation at power densities in the range 4.1011-6.1014 W/cm2 in TBKI and CERN were used. Results of detailed numerical simulations presented in the paper are in good agreement with the experimental data. Work done in collaboration with CERN, ITEP, and TBKI was aimed at the specification of requirements for a laser system that will be able to drive an ion source for the hadron collider (LHC) at CERN.

The simple physical model of highly charged ion generation in plasma produced by laser irradiation with long pulse duration (>1 ns) and moderate intensities (<1015/λ2 W/cm2μm2) is presented. In the frame of a single theory, most of the experimental results on plasma diagnostics are described in total. It is shown that plasma temperatures, ion charge states, and ion velocities as well as angular distributions of highly charged ions can be explained with good accuracy by collisional absorption of laser energy, hydrodynamic acceleration of forming plasma, and three-body recombination through highly exited levels during plasma expansion into vacuum. The general scalings for plasma parameters are derived on the basis of the model proposed.

Demonstration of matching a laser ion source to the GSI RFQ-Maxilac linear accelerator and the acceleration of a 1.8-mA current beam of Ta10+ ions up to 45 keV/u energy is presented. A 10J/μs CO2 laser has been used to produce a hot plasma plume, emitting highly charged tantulum ions. The correct geometry and potential distribution of the matching section has been designed in accordance with the results of computer simulations by using the AXCEL code. Measurements of the charge state distribution of the accelerated beam indicate that it contains about 70% Ta10+ and 30% Ta11+ ions.

Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 1011 C4+ ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and “hot” electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced.

Since 1976, the laser ion source (LIS) has been operated at the Laboratory of High Energies. At present, the LIS is used to perform experiments on relativistic beams of Li, B, C, N, O, F, Mg, and Si nuclei

Extensive studies of ion implantation into near surface areas of materials have demonstrated astonishing changes of such properties as surface tension, friction, and durability. The cost of implanted ions is currently rather high due to the limited ion current density of the usual ion sources, especially if ions from sources other than gaseous plasma must be used. The advent of the laser ion source, which offers many orders of magnitude higher current densities than classical ion sources, may change the scenario for a wide range of applications, making ion implantation as crucial a manufacturing technology in the future for other industries as it is today for microelectronics.

A modelization of the Rayleigh–Taylor instability, in the context of inertial confinement fusion, is made by means of a planar slab model whose main features are a sharp ablation front separating the slab and the expanding corona, absorption of constant intensity laser light at a critical surface, profiles for background flow variables consistent with hydrodynamic equations, and heat conduction present in the expanding corona. A sharp ablation front assumption (density at the critical surface is much less than the slab density, ρc/ρs ≪ 1) supposes that the ablated mass is small, so the model is valid for thick targets. Two main regimes are modelized, subsonic and sonic absorption. The growth rate of the instability is obtained, and its variation with kD and kxc is studied (k = perturbation wavenumber; D = slab thickness; xc = ablation to critical surfaces distance). The model shows stabilization over the classical Rayleigh–Taylor growth rate (γ = √kg). The stabilization mechanism is based on heat conduction near the ablation front.

Three gas lenses appear promising for fusion and other applications. We review progress of the understanding and scaling of two of these lenses and discuss their potential for industry, advanced research, and fusion.

Spherical gold Hohlraums were heated by the iodine laser ASTERIX IV (200 J/0.4 ns at 440 nm) and were used to investigate radiative heating of low-Z plastic foils at temperatures up to 100 eV by time-resolved XUV emission and absorption spectroscopy. Spectra of the reemitted radiation (the albedo) for different C-, O-, F-, or Cl-containing plastic materials are presented. Depending on the material, the typical total (frequency-integrated) reemission is in the range of ≈10% of the gold reemission. By measuring the absorption spectra it was possible to follow the burnthrough in carbon from the initial solid degenerate state up to a high ionization state with absorption lines due to hydrogen-like carbon corresponding to a temperature of about 100 eV. The propagation of the heat wave into the material also has been studied by observing the emission from boron tracer layers embedded at different depths in the plastic foil. The experimental observations are compared with MULTI simulations.

A new technique for levitating solid particles inside a vacuum chamber is developed using a proton beam. This new technique differs from the classical laser-levitation technique invented by Ashkin in that it does not heat up light-absorbing levitated particles to vaporization. This unique property of the method will make it possible to levitate real interplanetary dust particles in a vacuum chamber and study their spin-up dynamics in a ground-based laboratory. It is found that a flux of protons from a proton gun of ~1015 cm–2 sec–1 is needed to levitate a 10-mm particle. Confinement of the levitated particle can be achieved by a Z or θ pinch to create a gravity well, or by making the beam profile doughnut in shape.

This paper presents the results of a theoretical investigation of a laser-supported detonation wave (LDW) in a transverse magnetic field. A 1D problem of a steady-state wavefront structure is considered. The magnetic structure of the LDW is determined. Specific attention is focused on the stability conditions of a shock wavefront. The value of the induced (downstream) electric field strength is obtained from numerical calculations. The possibility of direct conversion of laser radiation energy into electricity in optical discharge plasma moving across an external magnetic field is considered. Such a device could be used in the energy supply systems of space vehicles.

High-intensity electron beams could be focused in low-frequency RF accelerators and induction linear accelerators by adding transverse components to the accelerating electric field. Calculations with a 3D code show that quasielectrostatic focusing is sufficient to transport kiloampere electron beams in RF accelerators and the high-energy sections of induction accelerators. The elimination of conventional magnetic focusing systems could lead to reductions in the volume and weight of high-current electron accelerators. Two novel quadrupole geometries are investigated: a periodic array of spherical electrodes with alternating displacements and a set of plate electrodes with elliptical apertures.