Warm Dense Matter Generation Research Articles

Quasi-monoenergetic carbon ions generation from a double-layer target driven by extreme laser pulses

High quality energetic carbon ions produced via laser-plasma have many applications in tumor therapy, fast ignition and warm dense matter generation. However, the beam achieved in current experiments is still limited by either a large energy spread or a low peak energy. In this paper, a hybrid scheme for the generation of quasi-monoenergetic carbon ions is proposed by an ultra-intense laser pulse irradiating a double-layer target. Multi-dimensional particle-in-cell (PIC) simulations show that the carbon ions are first accelerated via laser piston mechanism in the former carbon layer and then further accelerated by Coulomb repulsion force in the attached neon target. Since electrons are bunched synchronously in longitudinal and transverse direction by radiation reaction during the whole acceleration process, a quasi-monoenergetic carbon ion beam is eventually produced. In the following stage, the neon target provides the Coulomb field required for the continuous acceleration of the carbon ions which helps to prevent the carbon ion layer from diffusion. It is demonstrated that quasi-monoenergetic carbon ions with peak energy of 465 MeV u−1, energy spread of ∼13%, a divergence of ∼15∘, and laser-to-ion energy conversion of 20% can be achieved by using a laser pulse with intensity of 1.23 × 1023 W cm−2. An analytical model is also proposed to interpret the carbon ion acceleration, which is fairly consistent with the PIC simulations.

Investigation of resistive magnetic field generation by intense proton beams in dense plasmas

Current and future applications of intense proton sources abound, including radiography, cancer therapy, warm dense matter generation, and inertial confinement fusion. With increasingly efficient acceleration and focusing mechanisms, proton current densities may soon approach and exceed 1010 A/cm2, e.g., via intense laser drivers. Simulations have previously shown that in this current density regime, beam-induced field generation plays a significant role in beam transport through dense plasmas. Here, we present a theoretical model for the generation of resistive magnetic fields by intense proton beam transport through solid density plasmas. The theoretical evolution of the magnetic field profile is calculated using an analytic model for aluminum resistivity, heat capacity, and stopping power, applicable from cold matter to hot plasma. The effects of various beam and material parameters on the field are investigated and explained for both monoenergetic and Maxwellian proton beams. For a proton beam with Maxwellian temperature 5 MeV and total energy 10 J, the model calculates resistive magnetic fields up to 150 T in aluminum. The calculated field profiles from several beam cases are compared with 2D hybrid particle-in-cell simulations, with good agreement found in magnitude and time scale.

Transport of an intense proton beam from a cone-structured target through plastic foam with unique proton source modeling.

Laser-accelerated proton beams are applicable to several research areas within high-energy density science, including warm dense matter generation, proton radiography, and inertial confinement fusion, which all involve transport of the beam through matter. We report on experimental measurements of intense proton beam transport through plastic foam blocks. The intense proton beam was accelerated by the 10ps,700J OMEGA EP laser irradiating a curved foil target, and focused by an attached hollow cone. The protons then entered the foam block of density 0.38g/cm^{3} and thickness 0.55 or 1.00mm. At the rear of the foam block, a Cu layer revealed the cross sectionof the intense beam via proton- and hot electron-induced Cu-K_{α} emission. Images of x-ray emission show a bright spot on the rear Cu film indicative of a forward-directed beam without major breakup. 2D fluid-PIC simulations of the transport were conducted using a unique multi-injection source model incorporating energy-dependent beam divergence. Along with postprocessed calculations of the Cu-K_{α} emission profile, simulations showed that protons retain their ballistic transport through the foam and are able to heat the foam up to several keV in temperature. The total experimental emission profile for the 1.0mm foam agrees qualitatively with the simulated profile, suggesting that the protons indeed retain their beamlike qualities.

Progress of intense heavy ion beam driven high energy density physics

Intense ion beams can quasi-isometrically heat any high-density sample and generate warm dense matter (WDM) with large scale, uniform state distribution without any shock wave inside. This kind of driver provides a new opportunity for the laboratory high energy density physics (HEDP) research. The typical intense ion beam accelerators around the world, as well as their critical parameters and research plans of HEDP study are introduced.The progress of ion driven WDM generation and evolution using PIC and hydrodynamic simulations is shown. The high energy electron beam radiography technique with high spatial resolution, high temporal evolution, and high penetrating ability is also introduced. The collisional and charge transfer processes of the interaction between low-to-medium energy ion and plasma are analyzed. The nonlinear effect during the intense ion beam stopping and transportation process are presented.

Overheating instability of a thin conductor with respect to stratification

We consider an overheating instability of a thin (compared to the skin depth) conductor with respect to stratification at the stage when its resistivity rises up to an electrical explosion. Temperature perturbations under such conditions are shown to grow in proportion to resistivity. In the model, when resistivity is proportional to temperature, perturbations grow in proportion to temperature and hence exhibit no relative growth. For a conductor with initial thickness perturbations, temperature perturbations grow in proportion to resistivity and current action integral, i.e., somewhat faster than perturbations in the problem of constant thickness conductors. Comparison of our results with simulations of the growth of stratification during electrical heating of foils in warm dense matter generation systems demonstrates their close agreement.

The impact of three dimensional MHD instabilities on the generation of warm dense matter using a MA-class linear transformer driver

Warm dense matter is difficult to generate since it corresponds to a state of matter which pressure is order of magnitude larger than can be handled by natural materials. A diamond anvil can be used to pressurize matter up to one Gbar, this matter is at high density but at room temperature. High power lasers and heavy ion beams can generate warm dense matter on time scales where measuring quasi-static transport coefficients such as viscosity or heat conduction proves difficult since both experimental techniques relies on inertial confinement. We present here a third method to generate warm dense matter. It uses a pulsed-power driver which current rise time is substantially shortened by using a plasma opening switch, limiting the development of electrothermal instabilities. The switch relies on the implosion of a gas puff Z-pinch which carries most of the discharge current until the pinch reaches the sample. After that, the sample is compressed until it reaches the warm dense matter regime. Three-dimensional magnetohydrodynamics computations show that if the density of the gas is low enough no detectable instabilities (e.g. kinks and sausages modes) impede the remainder of the implosion.

Input energy measurement toward warm dense matter generation using intense pulsed power generator

In order to investigate properties of warm dense matter (WDM) in inertial confinement fusion (ICF), evaluation method for the WDM with isochoric heating on the implosion time-scale using an intense pulsed power generator ETIGO-II (∼1 TW, ∼50 ns) has been considered. In this study, the history of input energy into the sample is measured from the voltage and the current waveforms. To achieve isochoric heating, a foamed aluminum with pore sizes 600 μm and with 90% porosity was packed into a hollow glass capillary (ø 5 mm × 10 mm). The temperature of the sample is calculated from the numerical calculation using the measured input power. According to the above measurements, the input energy into a sample and the achievable temperature are estimated to be 300 J and 6000 K. It indicates that the WDM state is generated using the proposed method with ICF implosion time-scale.

Concept for Generation of Warm Dense Matter of Insulator due to Flyer Impact Accelerated by Electron Beam Irradiation using Intense Pulsed Power Generator

We have proposed a concept for generation method of warm dense matter (WDM) by using flyer impact accelerated by intense electron beams. To generate the warm dense matter by using flyer impact, the output current of electron beams generated by the intense pulsed-power generator as ETIGO-II is evaluated. The results denote that the beam current and the pulse duration are 11 kA and 50 ns, respectively. The achievable parameters of WDM by using flyer impact are estimated by the simplified model. It indicated that the sample temperature achieves the provided electron beams with lower conversion efficiency.

Generation of warm dense matter using an argon based capillary discharge laser

Argon based capillary discharge lasers operating in the extreme ultra violet (EUV) at 46.9 nm with output up to 0.5 mJ energy per pulse and repetition rates up to 10 Hz are capable of focused irradiances of 109–1012 W cm−2 and can be used to generate plasma in the warm dense matter regime by irradiating solid material. To model the interaction between such an EUV laser and solid material, the 2D radiative-hydrodynamic code POLLUX has been modified to include absorption via direct photo-ionisation, a super-configuration model to describe the ionization-dependent electronic configurations and a calculation of plasma refractive indices for ray tracing of the incident EUV laser radiation. A simulation study is presented, demonstrating how capillary discharge lasers of 1200 ps pulse duration can be used to generate warm dense matter at close to solid densities with temperatures of a few eV and energy densities up to 1 × 105 J cm−3. Plasmas produced by EUV laser irradiation are shown to be useful for examining the properties of warm dense matter as, for example, plasma emission is not masked by hotter, less dense plasma emission that occurs with visible/infra-red laser target irradiation.

Feasibility of warm dense matter generation using aluminum and copper foil electric explosion under the PHELIX facility current drive

This paper investigates the feasibility of using the PHELIX facility for generation of warm dense matter (WDM), i.e., substance at densities of the order of 0.01–1.00 of the solid matter density and a temperature of 1–10 eV, by electric explosion of a thin cylindrical metal foil enclosed in an insulator. It has been shown this system can be used to produce a significant volume of uniform WDM with a density of 0.1–1.0 g/cm3 and a temperature of 3–4 eV, sufficient for electrical measurements. A method of determining WDM parameters based on electrical measurements and foil boundary velocimetry is described.

Исследование возможности использования установки PHELIX для получения теплого плотного вещества при электровзрыве алюминиевой и медной фольги

Исследование возможности использования установки PHELIX для получения теплого плотного вещества при электровзрыве алюминиевой и медной фольги

Warm Dense Matter Generation and DD Synthesis at Vacuum Discharge with Deuterium‐Loaded Pd Anode

AbstractThe energetic ions and DD neutrons from microfusion at the interelectrode space of a low energy nanosecond vacuum discharge with deuterium‐loaded Pd anode has been demonstrated recently. To understand better the physics of fusion processes the detailed PIC simulation of the discharge experimental conditions have been developed using a fully electrodynamic code KARAT. The dynamics of main charge particle species was recon‐structed in time and interelectrode space. The principal role of a virtual cathode (VC) and the corresponding single and double potential well formed in the interelectrode space are recognised. The calculated depth φ of the quasistationary potential well (PW) of the VC is about 50‐60 kV, and the D+ ions being trapped by this well accelerate up to energy values needed to provide collisional DD nuclear synthesis. Both experiment and PIC simulations illustrate very favourable scaling of the fusion power density at decreasing of VC radius (∼φ2/r4VC) for the chosen inertial electrostatic confinement fusion scheme based on miniature nanosecond vacuum discharge. Meanwhile, the initial stage of discharge is understood still poorly. When voltage is applied, the electron beam extracted from cathode starts to interact with the surface of deuterium‐ loaded Pd anode. This early stage of discharge manifests sometime the peaks registered by photomultipliers which are similar to neutron ones from time‐of‐flight measure under the study of collisional DD synthesis at the further stages of discharge. The detailed study of Pd anode surface morphology have been performed and recognized, in particular, the number of various pores and craters of different sizes. We remark that besides of rather usual craters (due to electron beams – anode interaction) some of the craters on the Pd anode surface may correspond to anode ectons (explosive centres) and consider their possible nature. Specifics of warm dense matter (WDM) generated at different stage of discharge is discussed. The data obtained are compared with recent results on initiation of DD reactions by electron beams at deuterium ‐loaded Pd foils and correspondent data on their surface morphology (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Generation of warm dense matter and strongly coupled plasmas using the High Radiation on Materials facility at the CERN Super Proton Synchrotron

A dedicated facility named High Radiation on Materials (HiRadMat) is being constructed at CERN to study the interaction of the 450 GeV protons generated by the Super Proton Synchrotron (SPS) with fixed solid targets of different materials. The main purpose of these future experiments is to study the generation and propagation of thermal shock waves in the target in order to assess the damage caused to the equipment, including collimators and absorbers, in case of an accident involving an uncontrolled release of the entire beam at a given point. Detailed numerical simulations of the beam-target interaction of several cases of interest have been carried out. In this paper we present simulations of the thermodynamic and the hydrodynamic response of a solid tungsten cylindrical target that is facially irradiated with the SPS beam with nominal parameters. These calculations have been carried out in two steps. First, the energy loss of the protons is calculated in the solid target using the FLUKA code [Fasso et al., “FLUKA: A multi-particle transport code,” Report Nos. CERN-2005-10, INFN/TC-05/11, and SLAC-R-773, 2005; Fasso et al., Conference on Computing in High Energy and Nuclear Physics, La Jolla, CA, 24–28 March 2003] and this energy loss data is used as input to a sophisticated two-dimensional hydrodynamic code, BIG2 [Fortov et al., Nucl. Sci. Eng. 123, 169 (1996)], which is based on a Godunov-type numerical scheme. The transverse intensity distribution in the beam focal spot is Gaussian. We consider three different sizes of the focal spot that are characterized by standard deviations, σ=0.088, 0.28, and 0.88 mm, respectively. This study has shown that the target is severely damaged in all the three cases and the material in the beam-heated region is transformed into warm dense matter including a strongly coupled plasma state. This new experimental facility can therefore also be used for dedicated experiments to study high energy density matter.

Laser acceleration of low emittance, high energy ions and applications

Abstract Laser-accelerated ion sources have exceptional properties, i.e. high brightness and high spectral cut-off (56 MeV at present), high directionality and laminarity (at least 100-fold better than conventional accelerators beams), short burst duration (ps). Thanks to these properties, these sources open new opportunities for applications. Among these, we have already explored their use for proton radiography of fields in plasmas and for warm dense matter generation. These sources could also stimulate development of compact ion accelerators or be used for medical applications. To extend the range of applications, ion energy and conversion efficiency must however be increased. Two strategies for doing so using present-day lasers have been successfully explored in LULI experiments. In view of applications, it is also essential to control (i.e. collimate and energy select) these beams. For this purpose, we have developed an ultra-fast laser-triggered micro-lens providing tuneable control of the beam divergence as well as energy selection. To cite this article: J. Fuchs et al., C. R. Physique 10 (2009).