Beam Plasma Interaction Experiments Research Articles

Active Experiments in Space: The Future

Planned active space experiments and ideas for future active space experiments are reviewed. Three active experiments being readied are DSX (Demonstration and Space eXperiments), SMART (Space Measurement of Rocket-released Turbulence), and BeamPIE (Beam Plasma Interaction Experiment). Ideas for future experiments include relativistic-electron-beam experiments for magnetic-field-line tracing, relativistic-electron-beam experiments to probe the middle atmosphere, plasma-wave launching using superparamagnetic-nanoparticle amplification of magnetic fields, the heavy-ion mass loading of collisionless magnetic-field-line reconnection, the use of electrostatically charged tethers to pitch-angle scatter radiation-belt particles, cold plasma releases to modify magnetospheric plasma physics, and neutral-gas releases to enhance neutral-particle imaging of the magnetosphere. Technologies that are being developed to enable future space active experiments are reviewed: this includes the development of compact relativistic accelerators, superparamagnetic particle amplified antennae, CubeSats, and a new understanding of how to control dynamic spacecraft charging. New capabilities to use laboratory facilities to design space active experiments as well as new computer-simulation capabilities to design and understand space active experiments are reviewed.

Astrophysical naturally moderated classical positron beam interaction with nonlinear waves in nonextensive astrophysical plasmas

The positron acoustic shock and solitary wave are explored in nonextensive electron-positron-ion plasma. The plasma system under-consideration, consists of a classical positron beam, q distributed electrons and positively charged bulky ions constitute a neutralizing background. The nonlinear Korteweg-de Vries and Burger equations are derived by employing the standard reductive perturbation method. The positron acoustic wave in linear limit is also discussed for dissipative as well as nondissipative cases of nonextensive plasmas. The plasma parameters such as, the concentration of neutralizing ions background, beam velocity, temperature and q parameter of the nonextensive electrons are noticed to significantly affect the positron acoustic shock and solitary waves. Our findings may be helpful in the understanding of laboratory beam plasma interaction experiments as well as the astrophysical nonextensive plasmas interacting with positron beam.

Impact of Positron Beam on Nonlinear Energy Transport in Electron–Ion Plasma

Interaction of classical positron beam with electron ion plasma is studied. Our main emphasis is on energy transport phenomena via propagation of nonlinear waves. The nonlinear waves are discussed in the limit of small amplitude through the reductive perturbation approach, as well as in the ambit of arbitrary amplitude through the energy conservation equation. The positron beam consists of positrons of finite pressure and its streaming velocities are in classical realm. Energy transport decelerates as the beam concentration and its pressure are enhanced. At higher streaming speeds of positron's beam, the energy transport is hindered due to plasma compression. The nonlinear wave is enfeebled as the parameter kappa of superthermal electrons is escalated. We have also discussed the single positron beam streaming instability. Our findings may be helpful in the understanding of laboratory beam plasma interaction experiments as well as the space and astrophysical plasmas with effects of superthermality and inte...

Ion acoustic shock waves in presence of superthermal electrons and interaction of classical positron beam

The effect of positron beam on the ion-acoustic shock wave is studied. The plasma system under-consideration consists of inertial ions and superthermal electrons and the positron beam with classical streaming velocities. Kinematic viscosity of the ions component is responsible of the dissipation in plasma system. The Burgers equation has been derived by employing the reductive perturbation method. It is noticed that both the amplitude and steepness of the ion-acoustic shock wave accrue, as the spectral index of the superthermal electrons, and concentration of impinging positron beam are enhanced. However, the shock amplitude is found to diminish as the beam streaming velocity and temperature ratio of positrons to electrons are increased in the plasma system. Our findings may be helpful in the understanding of laboratory beam plasma interaction experiments as well as the space and astrophysical plasmas with effects of superthermality and interacting beam.

Activities on heavy ion inertial fusion and beam-driven high energy density science in Japan

Recent research activities in Japan relevant to heavy ion fusion (HIF) are presented. During the past two years, significant progress in HIF and high energy density (HED) physics research has been made by a number of research groups in universities and accelerator facilities. Evolutions in phase space during the longitudinal compression of intense beams were investigated at UU–NUT–TIT. Beam–plasma interaction experiments and related theoretical studies are in progress at RLNR-TIT. In the study, shock-heated hydrogen was used for the interaction experiments as a well-defined non-ideal-plasma target. In the beam–plasma interaction experiments, a special emphasis is placed on an evaluation of non-linear effects on the stopping power in a beam-heated plasma target. A direct–indirect hybrid scheme of a beam-driven ICF target has been proposed and discussed at UU. In the same group, a method for controlling the Rayleigh–Taylor instability in imploding fuel target has been proposed using oscillating heavy ion beams (HIBs). Core dynamics of the impact ignition has been investigated both experimentally and numerically at ILE—Osaka. Dense plasmas driven by intense ion beams and/or a pulse powered device, were evaluated by a group of DES-TIT, concerning the researches on HED and warm dense matter (WDM) physics. A quasi-statically tamped target was proposed to make a well-defined, warm dense state for equation-of-state (EOS) studies based on ion accelerators. The potentiality of the new facility planned at KEK was evaluated by a collaborating group of TIT–UU–KEK, which can extend the parameter regime for laboratory experiments to study the properties of matter under extreme conditions. A possible method to make a high-pressure condition for study of the planetary science was discussed as a short-term subject of intense HIBs.

Time-resolved measurement of a shock-driven plasma target for interaction experiments between heavy ions and plasmas

To observe nonlinearity in the stopping power of a nonideal plasma for heavy ions, we are planning a beam-plasma interaction experiment using 10−100 keV∕u projectiles. For the interaction experiment, a nonideal hydrogen plasma target was developed by means of a shock technique. Time-resolved spectroscopic measurements determined the temporal evolution of the electron density and temperature of the shock plasma. These data revealed that the structure behind the shock front has an appropriate spatial and temporal distribution to be used as a target. We also evaluated the temporal evolution of the Coulomb coupling constant and the degree of ionization at a fixed position where the projectiles are injected. We discuss the feasibility of the nonlinear stopping experiment by evaluating the beam-plasma coupling constant expected from the measured plasma parameters.

Interaction experiments using thin-foil-discharge warm-dense plasma

We developed a thin-foil-discharge (TFD) plasma target for beam–plasma interaction experiments. A discharge current of several tens of kilo-amperes rapidly heated and ionized a thin aluminum foil of sub- to several micrometers thick. The target areal density seen by projectiles was expected to be almost constant during several hundred nanoseconds from the ignition of the discharge because the size of the thin foil was chosen to be much larger than the cross-section of the incident beam. The optical observation of the plasma using a fast framing camera showed that the TFD plasma expanded one-dimensionally in the early stage of the discharge. We determined the plasma density and temperature from the observed plasma thickness and the deposited electrical power with equation-of-state data. A one-dimensional plasma expansion model was developed and used to examine the expected plasma parameters under various initial conditions. We also performed beam–plasma interaction experiments with fully stripped ions of 4.3 MeV / u . The energy loss of silicon ions was measured as a function of time by the TOF method.

Development of a non-ideal plasma target for non-linear beam–plasma interaction experiments

A shock-driven plasma target was developed to examine non-linear interactions between low-energy heavy ions and cold-dense plasmas. MD calculations predicted that beam–plasma coupling constant γ ∼ 0.1 must be achieved to observe the non-linearity, which corresponds to the plasma coupling constant Γ ≈ 0.2 for projectiles of v proj ≈ 10 keV / u and q ≈ 2 . One-dimensional numerical estimations using SESAME equation of state showed that a shock wave propagating in 5-Torr H 2 gas with 47 km/s must be produced to satisfy Γ ≈ 0.2 . Utilizing an electromagnetic shock tube with a peak current of 50 kA and a current rise time of 800 ns, we achieved a shock speed of 45 km/s. The electron density distribution of the shock-produced plasma along the beam axis was measured by a Mach–Zehnder interferometer. From this measurement we confirmed that the electron density was over 10 17 cm - 3 and the homogeneity was acceptable during several hundred nanoseconds. The electron temperature was also determined by optical spectroscopic measurements. The Coulomb coupling constant was evaluated using these experimental data to investigate feasibility of the beam–plasma interaction experiments.

Overview of Russian heavy-ion inertial fusion energy program

The activities overview of Russian laboratories on Heavy-Ion Fusion is presented. The new data on development of the power plant concept based on direct drive of cylindrical DT target by intense 500 MeV/u ion beam in fast ignition mode and two sections wetted liquid wall reactor chamber with lithium–lead blanket are presented. A heavy-ion driver system providing consequent compression and ignition of the cylindrical DT target is described. Data on repetitive energy fluxes generated by the 750 MJ of microfusion explosion are given. The design of the thin liquid wall reactor chamber is specified. The behavior of the liquid film at the first wall and the blanket material under a pulsed energy flux loading is emphasized. The energy conversion thermal scheme and power plant output parameters are presented. The state of the art of the ITEP-TWAC accelerator facility operation and new results of current beam–plasma interaction experiments are discussed. This work has been done under the auspices of the Scientific Council of Russian Academy of Sciences “Analysis of Energy Systems” under the chairmanship of academician V.I. Subbotin.

Present and future perspectives for high energy density physics with intense heavy ion and laser beams

Intense heavy ion beams from the Gesellschaft für Schwerionenforschung (GSI, Darmstadt, Germany) accelerator facilities, together with two high energy laser systems: petawatt high energy laser for ion experiments (PHELIX) and nanosecond high energy laser for ion experiments (NHELIX) are a unique combination to facilitate pioneering beam-plasma interaction experiments, to generate and probe high-energy-density (HED) matter and to address basic physics issues associated with heavy ion driven inertial confinement fusion. In one class of experiments, the laser will be used to generate plasma and the ion beam will be used to study the energy loss of energetic ions in ionized matter, and to probe the physical state of the laser-generated plasma. In another class of experiments, the intense heavy ion beam will be employed to create a sample of HED matter and the laser beam, together with other diagnostic tools, will be used to explore the properties of these exotic states of matter. The existing heavy ion synchrotron facility, SIS18, deliver an intense uranium beam that deposit about 1 kJ/g specific energy in solid matter. Using this beam, experiments have recently been performed where solid lead foils had been heated and a brightness temperature on the order of 5000 K was measured, using a fast multi-channel pyrometer that has been developed jointly by GSI and IPCP Chernogolovka. It is expected that the future heavy ion facility, facility for antiprotons and ion research (FAIR) will provide compressed beam pulses with an intensity that exceeds the current beam intensities by three orders of magnitude. This will open up the possibility to explore the thermophysical and transport properties of HED matter in a regime that is very difficult to access using the traditional methods of shock compression. Beam plasma interaction experiments using dense plasmas with a Γ-parameter between 0.5 and 1.5 have also been carried out. This dense Ar-plasma was generated by explosively driven shockwaves and showed enhanced energy loss for Xe and Ar ions in the energy range between 5.9 to 11.4 MeV.

Stopping of low-energy highly charged ions in dense plasmas

Stopping power of low-energy, highly charged projectiles in cold dense plasmas was numerically investigated to search realistic parameters for beam–plasma interaction experiments using ≈10–100 keV/u projectiles delivered by a 1.7 MV electrostatic accelerator. In order to evaluate the energy loss, a simple Molecular Dynamics (MD) computer code was applied. If the projectile velocity was as low as the thermal velocity of plasma electrons, and the projectile charge was sufficiently high, nonlinear stopping was observed even for weakly nonideal plasma targets with Γ ≈ 0.1 . According to a numerical analysis on the charge state distribution coupled with an energy loss calculation, projectiles with such a high charge state are rapidly lost by the strong recombination owing to electrons loosely trapped by the projectile, as well as the residual hydrogen atoms in the plasma.

Plasma physics with intense laser and ion beams

The unique combination of an intense heavy ion beam and a high-energy Nd:glass laser system at Gesellschaft für Schwerionenforschung (GSI-Darmstadt) facilitates pioneering beam-plasma interaction experiments and thus allows to address basic physics issues associated with heavy ion-driven inertial fusion. The deposition power of the intense heavy ion beam from the synchrotron has recently been increased to 1 kJ/g. The hydrodynamic response of solid targets was measured. A comparison with detailed numerical simulations attributes the target response to a pressure pulse of 3 GPa at a maximum temperature of 2500 K. Beam plasma interaction experiments to measure the stopping power of laser plasmas for heavy ion beams have been performed and show an increased energy loss for Ni ions in a 60 eV dense carbon plasma. Subsequently performed time-resolved charge-state measurements indicate that the increased stopping power can partially be attributed to a high charge state of the beam ions traversing the plasma. Improved plasma diagnostic by high-resolution spectroscopy revealed the unexpected existence of He-like resonance and intercombination lines (He α = 1s2p 3P 1–1s 2 and Y α = 1s2p 3P 1–1s 2) of fluorine even for a modest laser intensity of 5 × 10 11 W/cm 2.

Intense electron beams produced in pseudospark and PCOHC for beam–plasma interaction experiments

High-voltage hollow-cathode glow discharges are used to generate intense pulsed electron beams with remarkable parameters. A comparison of the electron beam characteristics and the development of beam-induced plasma in the drift space is made for two of these configurations: preionization controlled open ended hollow cathode (PCOHC) and pseudospark, both in a multigap geometry. The dependency of electron beam parameters on external capacity, gas pressure and breakdown voltage is discussed.

Development of a laser-produced plasma target for beam–plasma interaction researches

A laser-produced plasma target system was developed for beam–plasma interaction experiments concerning heavy-ion inertial fusion. Irradiating a small particle of lithium hydride (LiH) with a pulsed laser, transformed the particle into a plasma. The isotropy of the plasma expansion was monitored by charge collectors. The electron density distribution was measured by interferometry. For particle sizes below and irradiation energies above certain critical values, we obtained a spherically symmetric Gaussian-like density distribution and a high degree of ionization. The expected density and size of the spherical plasma as a target for ion beams are roughly ∼10 18 cm −3 and ∼1 mm, respectively.

Plasma diagnostics using Kα satellite emission spectroscopy in light ion beam fusion experiments

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.

Effects of multiple ionization on the Kα spectrum of aluminum in intense lithium beam experiments

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.

Energy loss of fast heavy ions in plasmas

Interaction processes of heavy ions and ionized matter have been investigated experimentally. A Monte Carlo code to simulate charge exchange and energy loss processes in a plasma environment has been developed to plan the experiments, to analyze the results, and to investigate the influence of magnetic fields on the particle trajectories inside the plasma target. The first results of the beam plasma interaction experiments are: — The stopping power of ionized matter is increased compared to that of cold, non-ionized matter. This effect is especially pronounced at low ion energies ( E < 100 keV/u) where an enhancement factor of up to 40 has been observed. At higher energies ( E > 1MeV/u) this effect is less dramatic, but is still on the order of 2–3, depending on the ion species. — The charge state of ions traversing a fully ionized plasma is increased due to reduced capture cross sections of free plasma electrons. — It is possible to focus intense heavy ion beams of high magnetic rigidity using a plasma lens. This ideal focusing device achieves a high focusing power for ion beams almost comparable to optical systems for intense beams from high power lasers. — Energetic ion beams are very well suited to heat cylindrical target volumes and to create a dense plasma. The characteristic inner-shell target and projectile X-rays provide a tool to analyze the hydrodynamic behavior of beam heated targets with space and time resolution.

Beam–plasma interaction experiments with heavy-ion beams

The progress of the experimental research program at GSI for studying beam-plasma interaction phenomena is reported. Heavy-ion beams from the new accelerator facility SIS/ESR at GSI-Darmstadt are now available for experiments, and will soon deliver ≥ 109 particles per pulse in 100 ns. Focused on a small sample of matter, the beams will be able to produce a high-density plasma and to permit investigation of interaction processes of heavy ions with hot ionized matter.For the intense beam from the new heavy-ion synchrotron (SIS), a fine-focus system has been designed to produce a high specific deposition power beam for target experiments with a beam-spot radius of 100 μm. We further discuss improvements of this lens system by nonconventional focusing devices such as plasma lenses.Intense-beam experiments at the RFQ Maxilac accelerator at GSI have already produced the first heavy-ion-induced plasma with a temperature of 0.75 eV. New diagnostic techniques for investigating ion-beam-induced plasmas are presented. The low-intensity beam from the GSI UNILAC has been used to measure energy deposition profiles of heavy ions in hot ionized matter. In this experiment an enhancement of the stopping power for heavy ions was observed. The current experimental research program tests basic plasma theory and addresses key issues of inertial confinement fusion driven by intense heavy-ion beams.

Beam-plasma interaction experiments at GSI: An experimental program to study high energy density in matter by means of intense heavy-ion beams

Heavy-ion beams of high instantaneous beam power will soon be available from the new accelerator facility (SIS/ESR) at GSI. Focussed on a small target

Beam–plasma instabilities and the beam–plasma discharge

Using a new electron gun, a number of measurements bearing on the generation of beam–plasma discharge (BPD) in WOMBAT (waves on magnetized beams and turbulence) [R. W. Boswell and P. J. Kellogg, Geophys. Res. Lett. 10, 565 (1983)] have been made. A beam–plasma discharge is an rf discharge in which the rf fields are provided by instabilities [W. D. Getty and L. D. Smullin, J. Appl. Phys. 34, 3421 (1963)]. The new gun has a narrower divergence angle than the old, and comparison of the BPD thresholds for the two guns verifies that the BPD ignition current is proportional to the cross-sectional area of the plasma. The high-frequency instabilities, precursors to the BPD, are identified with the two Trivelpiece–Gould modes [A. W. Trivelpiece and R. W. Gould, J. Appl. Phys. 30, 1784 (1959)]. Which frequency appears depends on the neutral pressure. The measured frequencies are not consistent with the simple interpretation of the lower frequency as a Cerenkov resonance with the low-Trivelpiece–Gould mode; it must be a cyclotron resonance. As is generally true in such beam–plasma interaction experiments, strong low-frequency waves appear at currents far below those necessary for BPD ignition. These low-frequency waves are shown to control the onset of the high-frequency precursors to the BPD. A mechanism for this control is suggested, which involves the conversion of a convective instability to an absolute one by trapping of the unstable waves in the density perturbations of the low-frequency waves. This process greatly reduces the current necessary for BPD ignition.