The article presents the results of the experimental research on precision measurement of total stopping range and energy deposition function of intermediate and heavy ion beams in cold solid matter. The “thick target” method proves to be appropriate for this purpose. Two types of detectors were developed which provide an error of the total stopping range measurement of less than 3% and of the beam energy deposition function of about 7%. The experiments with 58Ni+26, 197Au+65, and 238U+72 ion beams in the energy range 100–300 MeV/u were performed on SIS-18 (Gesellschaft für Schwerionenforschung, Darmstadt) in 1999–2001. The measured data on the total stopping ranges for the above ion species in bulk and foiled Al and Cu targets are presented. The investigation showed that there is a noticeable discrepancy between the measured stopping ranges and the theoretically predicted ones. Also, it was shown that realistic ion energy deposition depends on the type of target (bulk or foiled). Further investigation is necessary to clarify the latter.

The interaction process between fast heavy ions and dense plasma was experimentally investigated. We injected 4.3-MeV/u or 6.0-MeV/u iron ions into a z-pinch-discharge helium plasma and measured the energy loss of the ions by the time of flight method. The energy loss of 4.3-MeV/u ions fairly agreed with theoretical prediction when the electron density of the target was on the order of 1018 cm−3. With increasing electron density beyond 1019 cm−3, the difference between the experiment and the theory became remarkable; the experimental energy loss was 15% larger than the theoretical value at the peak density. For 6.0-MeV/u ions, the deviation from the theory appeared even at densities below 1019 cm−3. These discrepancies indicated that density effects such as ladderlike ionization caused the enhancement of the projectile mean charge in the target.

The final beam transport in the reactor chamber for heavy ion fusion in preformed plasma channels offers many attractive advantages compared to other transport modes. In the past few years, experiments at the Gesellschaft für Schwerionenforschung (GSI) accelerator facility have addressed the creation and investigation of discharge plasmas, designed for the transport of intense ion beams. Stable, self-standing channels of 50 cm length with currents up to 55 kA were initiated in low-pressure ammonia gas by a CO2-laser pulse along the channel axis before the discharge is triggered. The channels were characterized by several plasma diagnostics including interferometry and spectroscopy. We also present first experiments on laser-guided intersecting discharges.

We consider beams that are described by a four-dimensional (4D) transverse distribution f (x, y, x′, y′), where x′ ≡ px /pz and z is the axial coordinate. A two-slit scanner is commonly employed to measure, over a sequence of shots, a two-dimensional (2D) projection of such a beam's phase space, for example, f (x, x′). Another scanner might yield f (y, y′) or, using crossed slits, f (x, y). A small set of such 2D scans does not uniquely specify f (x, y, x′, y′). We have developed “tomographic” techniques to synthesize a “reasonable” set of particles in a 4D phase space having 2D densities consistent with the experimental data. We briefly summarize one method and describe progress in validating it, using simulations of the High Current Experiment at Lawrence Berkeley National Laboratory.

Ion–electron two-stream instabilities in high intensity heavy ion fusion beams, described self-consistently by the nonlinear Vlasov–Maxwell equations, are studied using a three-dimensional multispecies perturbative particle simulation method. Large-scale parallel particle simulations are carried out using the recently developed Beam Equilibrium, Stability, and Transport (BEST) code. For a parameter regime characteristic of heavy ion fusion drivers, simulation results show that the most unstable mode of the ion–electron two-stream instability has a dipole-mode structure, and the linear growth rate decreases with increasing axial momentum spread of the beam particles due to Landau damping by the axial momentum spread of the beam ions in the longitudinal direction.

Key issues of heavy ion beam (HIB) inertial confinement fusion (ICF) include an efficient stable beam transport, beam focusing, uniform fuel pellet implosion, and so on. To realize a HIB fine focus on a fuel pellet, space-charge neutralization of incident focusing HIB is required at the HIB final transport just after a final focusing element in an HIB accelerator. In this article, an insulator annular tube guide is proposed at the final transport part, through which a HIB is transported. The physical mechanism of HIB charge neutralization based on an insulator annular guide is as follows: A local electric field created by HIB induces local discharges, and plasma is produced on the insulator inner surface. Then electrons are extracted from the plasma by the HIB net space charge. The electrons emitted neutralize the HIB space charge well.

Quasi-linear analysis demonstrates that intense and nonrelativistic proton beams do not lose collectively their kinetic energy through transverse Weibel electromagnetic instabilities when interacting with supercompressed plasmas of inertial confinement interest.

Highly ionized plasmas are being considered as a medium for charge neutralizing heavy ion beams in order to focus beyond the space-charge limit. Calculations suggest that plasma at a density of 1–100 times the ion beam density and at a length ∼0.1–2 m would be suitable for achieving a high level of charge neutralization. An Electron Cyclotron Resonance (ECR) source has been built at the Princeton Plasma Physics Laboratory (PPPL) to support a joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization with plasma. The ECR source operates at 13.6 MHz and with solenoid magnetic fields of 1–10 gauss. The goal is to operate the source at pressures ∼10−6 Torr at full ionization. The initial operation of the source has been at pressures of 10−4–10−1 Torr. Electron densities in the range of 108 to 1011 cm−3 have been achieved. Low-pressure operation is important to reduce ion beam ionization. A cusp magnetic field has been installed to improve radial confinement and reduce the field strength on the beam axis. In addition, axial confinement is believed to be important to achieve lower-pressure operation. To further improve breakdown at low pressure, a weak electron source will be placed near the end of the ECR source. This article also describes the wave damping mechanisms. At moderate pressures (> 1 mTorr), the wave damping is collisional, and at low pressures (< 1 mTorr) there is a distinct electron cyclotron resonance.

We first pay attention to the inflight charge state distribution in a Pb ion beam propagating in a reactor-sized chamber delimited by metallic walls. We thus compare Livermore (code BIC) and Orsay (code BPIC) distributions in the presence of a residual Flibe gas pressure. Next, we replace the electron plasma due to Flibe ionization by a gliding plasma produced by the polarization of the incoming ion beam on insulating walls. Corresponding electrons, when attracted by the beam, are demonstrated to yield a very efficient current neutralization.

It is cylindrical converters that are generally considered for the purpose of changing the ion beam energy into X rays, with their irradiation to be provided through the cylinder end. This article studies a target having a disk-shaped converter to be irradiated sideways. It may be practical when one fails to overcome difficulties with the focusing of ion beams into a spot of a diameter smaller than a few millimeters.

In this article, we discuss the modifications that occur in the brightness and gain of a longitudinal wiggler-free electron laser with the aid of induced betatron oscillation. Two novel approaches have been discussed to improve the gain of the system. In the first scheme, an auxiliary undulator field with betatron oscillations brings in additional bunching and results in enhanced gain. In the second scheme, an axial magnetic field is tuned to provide additional bunching for gain enhancement.

Ablation depths of stainless steel targets irradiated by 80-fs laser pulses at a flux F ≤ 40 J/cm2 (intensity ≤ 5 × 1014 W/cm2) in the presence of air at atmospheric pressure are experimentally measured. These values are lower than the theoretical predictions for metal targets in vacuum. Results are analyzed on the basis of the role of the ambient gas and of crater formation on the behavior of the ablated material.

The laser-induced plasma obtained from the liquid target and expanding across a steady magnetic field has been studied using atomic emission spectroscopy. The line emission from the plasma was enhanced (>1.5 times) in the presence of a magnetic field, whereas background emission decreases. Enhancement in line intensity was found to be mainly a function of plasma beta (β). An increased rate of three-body recombination in plasma particles due to the cooling of the plasma during its expansion and an increase in effective plasma density as a result of its confinement seems to be the reason behind this enhancement.

The high precision X-ray spectroscopy studies of plasma created from the CO2 clusters in gas jet targets by the ultrashort laser pulses (35 and 60 fs duration) were performed at the intensities IL ∼ 1017–1018 W cm−2. The spectral line shape of the H-like and He-like oxygen ions gains an asymmetry with increasing the laser pulse intensity. Theoretical modeling of the line shape shows that the asymmetry can be explained by absorption of the Doppler-shifted line radiation from the essential fraction of ions (over 10−3) with energies above 1 MeV due to photoionization of inner shells of carbon ions. The results obtained demonstrate measurement capabilities of the X-ray spectral measurements of multicharged ions accelerated during the interaction with a laser radiation.

By means of a new two-dimensional three-temperature hydrodynamical code we considered the burning of the deuterium fuel with a small amount of a catalytic 3He in a cylindrical channel. To reduce the requirements for an ignition heavy ion beam we used an irradiated DT tablet (Jbeam = 4·106 TW/g, Ebeam = 0.5 MJ). We received the steady burning wave for the parameter ρr [gsim ] 8–10 g/cm2 with a gain coefficient G [gsim ] 30 in comparison with such parameters for the DT fuel G ∼ 140 at ρr = 0.5 g/cm2. Upon reducing the parameter ρr ∼ 4 g/cm2, the burning wave disappears moving along a channel. A part of the deuterium fuel burns with a reduced gain coefficient of 3–5. In the case of large fuel densities ρ = 100 g/cm3, our estimates show extremely large requirements for a compression beam 450–750 MJ for ρr ∼ 4 g/cm2.

This study reports on the optimization of the radio frequency capture phase during the operational cycle of the SIS-18 synchrotron at Gesellschaft für Schwerionenforschung, Darmstadt, Germany. The ion species studied were 238U+28 and 238U73+ at an injection energy of 11.4 MeV/u. The longitudinal relative momentum spread derived from Schottky spectra of the coasting beam at injection provides a value of |Δp/p0|full-width ∼ 5 × 10−3. Simulation results from the synchrotron tracking code ESME (FermiLab) were compared with beam-current profile measurements obtained from a pickup. To gain further insight, the Tomography program (European Organization for Nuclear Research) has been used to derive the longitudinal phase space development from waterfall plots of the measured beam current profile, which may then be compared against simulation. Possible causes of this nonadiabaticity are discussed and solutions are proposed.

We analyze the influence of a high-intensity laser field in the inverse mean free path of electrons moving through a degenerate electron gas. Our calculations are based on the random-phase-approximation formalism, in terms of the dielectric function of the medium, where the effects of the laser field are included in the dynamical response. The main effects on the slowing down of the electrons are studied as a function of the intensity and frequency of the laser field, as well as a function of the projectile velocity. A modification of the electron inverse mean free path for plasmon and electron-hole excitations is obtained due to multiphoton-exchange processes.

The optical emission spectra of the plasma generated by a 1.06-μm Nd:YAG laser irradiation of Al target in air was recorded and analyzed in a spatially resolved manner. Electron temperatures and densities in the plasma were obtained using the relative emission intensities and the Stark-broadened linewidths of Al(I) emission lines, respectively. The dependence of the electron density and temperature on the distance from the target surface and on the laser irradiance were manifested. We also discussed how the air takes part in the plasma evolution process and confirmed that the ignition of the air plasma was by the collisions between the energetic electrons and the nitrogen atoms through a cascade avalanche process.

Conclusive demonstration of electron-beam enhancement of ion charge states for the Metal Vapor Vacuum Arc (MEVVA) ion source was recently achieved using an external electron beam (E-MEVVA) in experiments performed jointly among the Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia, the High Current Electronics Institute (HCEI), Tomsk, Russia, and Brookhaven National Laboratory (BNL), USA. The E-MEVVA experiments were performed in Moscow and Tomsk with nearly the same design of ion sources. Results for lead and bismuth cathodes yielded maximum ion charge states of Pb7+ and Bi8+ for E-MEVVA, as compared to Pb2+ and Bi2+ for conventional MEVVA operation. Additional encouraging results were also obtained using a Z-discharge to produce an internal electron-beam (Z-MEVVA and LIZ-MEV).

On hand of 3D PIC simulations we show that in a strongly magnetized plasma a relativistic electron beam can be forced to emit highly coherent radio emission by self-induced nonlinear density fluctuations. Such slowly moving nonlinear structures oscillate with the local plasma frequency at which the relativistic electrons are scattered. Beam electrons dissipate a significant amount of their kinetic energy by inverse Compton radiation at a frequency of about γ2ωpe. Since the beam is sliced into pancake structures which experience the same electric field the inverse Compton scattering is coherent. Such a process is a very promising candidate for the coherent radio emission of pulsars.