Density Plasma Physics Research Articles

On the Thomas–Fermi model: Gabor J. Kalman's contribution and numerical approximations

AbstractIn this article, we would like to pay tribute to Gabor Kalman, outlining his contribution to a model widely used in dense plasma physics: the high‐temperature Thomas–Fermi model. The approach of Ruoxian Ying and Kalman relies on the separation of the bound and free electrons, a physically reasonable definition of the bound electrons, a description of the source density in the Poisson equation through the electron–ion and ion–ion pair correlation functions and a determination of the degree of ionization from the minimization of the total free energy. We also report on different approximations of the function , which is a cornerstone of the original Thomas‐Femi model.

Forty years developments of the Institute of Heavy Ion Physics, Peking University

<p indent="0mm">Institute of Heavy Ion Physics (IHIP) was founded in 1983. Under the direction of Prof. Jia’er Chen, IHIP has gone through about three stages. The first stage was from 1983 to about 1990. In this period, the research directions of particle accelerator, neutron physics, ion beam physics and medical physics were determined and 6 research groups of accelerator mass spectrometer (AMS), radio frequency quadrupole (RFQ), superconducting radio frequency (SRF), neutron physics, ion beam physics, medical physics and a laboratory of electrostatic accelerators were formed. The second stage was from 1990 to about 2010. In this period, the research work was progressed rapidly, and fruitful research achievements were obtained in above research fields. To meet the development of nuclear technology and its application, several new research directions have been developed in IHIP since about 2010, including laser plasma acceleration, nuclear materials, high energy density physics and plasma physics, and many important achievements have been obtained. The typical achievements obtained by IHIP include: AMS dating of the archeological sites and the oracle bones for the Project of Xia-Shang-Zhou Chronology, which made important contributions to the establishment of the chronological framework of Xia, Shang and Zhou dynasties; Design and manufacture of series RFQ accelerators with innovative structures such as integrated split ring RFQ, separated-function RFQ acceleration structure and high current deuterium ion RFQ accelerator; R&amp;D of SRF cavities of TESLA type with a high acceleration gradient above 32 MV/m or a high quality factor up to 2.0<x content-type="symbol">´</x>10¹⁰ and cavities for accelerating ions such as spoke and QWR cavities; DC-SRF photocathode injectors, proposed by IHIP are also developed, which can provide high-quality CW electron beams with low emittance and high average current intensity; the laser phase-stable acceleration mechanism, a new concept of laser plasma acceleration for ions, has been proposed and the first laser proton accelerator and irradiation facility in the world has been built with <sc>3–15 MeV</sc> energy with 1%–5% energy dispersion and 2–30 pC single bunch charge; investigation of material behaviors in extreme environments, including structural evolution in materials induced by ion irradiation, synergistic effects in structural materials in fusion reactors, and structural modification of materials via extreme conditions as a processing tool; the neutron emission process as manifested in high temperature fusion plasmas has been investigated through developing advanced neutron spectroscopy instrumentation in fusion reactors and the neutron induced nuclear reaction mechanism through both nuclear data measurements and the theoretical calculations of fission actinide nuclei; investigation of the relationship between the phenomenon of arousal and different parts of human brain by MRI brain imaging; the interaction law and mechanism between different chemical groups and electrical properties were revealed by systematically studying the chemical structure changes of four different polymers caused by ion irradiation; proposing a method to achieve stable radiation pressure acceleration of heavy ions from laser-irradiated ultrathin foils, where a high-<italic>Z</italic> material coating in front is used. After 40 years’ development, IHIP becomes an important unit for advanced research and student training in the field of nuclear technology and application in China. We believe that the IHIP will make more contributions to the nuclear science and technology of China in the future.

Development of Stochastic Voronoi Lattice Structures via Two-Photon Polymerization

ABSRACT Low-density polymer foams of varying sizes, shapes, and densities are of specific interest to the inertial confinement fusion (ICF) program and related high-energy density plasma physics research. Historically, these foams are comprised of polystyrene or other low atomic number materials and have densities in the 30 to 300 mg/cm3 range. However, at the lower end of this density range, these traditional polymer foams become fragile and difficult to cast and machine into the geometries needed. Recently, the need by experimentalists for materials with densities below 30 mg/cm3 has increased. To address these needs, we are developing three-dimensional (3-D) printing techniques to create high-precision, low-density, and repeatable complex lattice structures. Using two-photon polymerization 3-D printing, we recently developed the first 5 mg/cm3 low-density lattice structure having an annular hemispherical shape. These microscale to mesoscale structures were modeled and designed using the nTopology software, specifically utilizing the “Voronoi volume lattice” and “random points in body” option blocks. All printing operations were performed using the Nanoscribe Photonic Professional GT instrument. Characterization of these 3-D structures was conducted using various microscopic and X-ray tomographic imaging techniques. Overall printed part sizes ranged from 1 to 5 mm in diameter and were composed of lattice ligaments having thicknesses in the 3- to 5-µm range. These structures have been incorporated into ICF targets recently shot on both the University of Rochester’s Laboratory of Laser Energetics Omega laser and the National Ignition Facility.

Status of the FAIR facility in Darmstadt

The Facility for Antiproton and Ion Research (FAIR) is currently being built in Darmstadt, Germany. The SIS100 accelerator is at the heart of FAIR and will provide proton and heavy-ion beams for a variety of experiments. There are four main research pillars at FAIR specialized in the field of nuclear, hadron and elementary particle physics, atomic and antimatter physics, high density plasma physics, as well as applications in condensed matter physics, biology and the biomedical sciences. In these proceedings I briefly review the main research pillars of FAIR and the status of its realization.

XingGuang III laser facility and its experimental ability to drive high-energy particle beams

The XingGuang III (XGIII) laser facility at the Science and Technology on Plasma Physics Laboratory at the Laser Fusion Research Center is unique in the world and consists of one 0.7 PW picosecond beam, one 0.6 PW femtosecond beam and one 1 kJ nanosecond laser beam. The three laser beams with different wavelengths and durations can converge in the target chamber with high spatial and temporal synchronization. Because of its smart beam configurations, XGIII providesunique opportunities for multi-beam pump–probe experiments in research fields such as high-energy density physics, plasma physics and laboratory astrophysics. Laser-driven high-energy particle beams were experimentally investigated, and found to play an important role in pump–probe schemes. High-energy electrons, protons, positrons and their experimental scalings were obtained using the picosecond laser beam with an intensity of 1019 W cm−2. A two-beam pump–probe experiment was demonstrated in which the plasma channel of the femtosecond laser pulse propagating in underdense plasma was imaged by a proton beam driven by the picosecond laser. Furthermore, a three-dimensional reconstruction of the plasma structure may be achieved in multi-beam pump–probe experiments with XGIII.

A flat-field soft X-ray spectrometer for X-ray absorption spectroscopy measurement of warm dense matter

A flat-field soft X-ray spectrometer operating in the spectral range of 250–1240 eV was designed and built for warm dense matter and high-energy density plasma physics. It employs a grazing incidence toroidal mirror as a focusing optic, an aberration-corrected varied line-spacing concave grating with 2400 lines/mm as a dispersive element, and a charge coupled device as an X-ray detector. The dispersion and energy resolution are calibrated with a high-power laser-produced plasma and X-ray free electron laser sources. A resolving power over 370 was achieved over the entire spectral range. A super broadband spectrum in the range of 250–1000 eV was measured from the laser-produced bismuth plasma. The signal-to-noise ratio of 130 was obtained with an average of 10 pulses. These results demonstrate the capability of the spectrometer for single laser shot based experiments for warm dense matter and high energy density plasma research.

Nonlocal heat transport and improved target design for x-ray heating studies at x-ray free electron lasers

The extremely high power densities and short durations of single pulses of x-ray free electron lasers (XFELs) have opened new opportunities in atomic physics, where complex excitation-relaxation chains allow for high ionization states in atomic and molecular systems, and in dense plasma physics, where XFEL heating of solid-density targets can create unique dense states of matter having temperatures on the order of the Fermi energy. We focus here on the latter phenomena, with special emphasis on the problem of optimum target design to achieve high x-ray heating into the warm dense matter (WDM) state. We report fully three-dimensional simulations of the incident x-ray pulse and the resulting multielectron relaxation cascade to model the spatial energy density deposition in multicomponent targets, with particular focus on the effects of nonlocal heat transport due to the motion of high energy photoelectrons and Auger electrons. We find that nanoscale high-Z/low-Z multicomponent targets can give much improved energy density deposition in lower-Z materials, with enhancements reaching a factor of 100. This has three important benefits. First, it greatly enlarges the thermodynamic parameter space in XFEL x-ray heating studies of lower-Z materials. Second, it allows the use of higher probe photon energies, enabling higher-information content X-ray diffraction (XRD) measurements such as in two-color XFEL operations. Third, while this is merely one step toward optimization of x-ray heating target design, the demonstration of the importance of nonlocal heat transport establishes important common ground between XFEL-based x-ray heating studies and more traditional laser plasma methods.

Efficient picosecond x-ray pulse generation from plasmas in the radiation dominated regime

The efficient conversion of optical laser light into bright ultrafast x-ray pulses in laser created plasmas is of high interest for dense plasma physics studies, material science, and other fields. However, the rapid hydrodynamic expansion that cools hot plasmas has limited the x-ray conversion efficiency (CE) to 1% or less. Here we demonstrate more than one order of magnitude increase in picosecond x-ray CE by tailoring near solid density plasmas to achieve a large radiative to hydrodynamic energy loss rate ratio, leading into a radiation loss dominated plasma regime. A record 20% CE into hν>1 keV photons was measured in arrays of large aspect ratio Au nanowires heated to keV temperatures with ultrahigh contrast femtosecond laser pulses of relativistic intensity. The potential of these bright ultrafast x-ray point sources for table-top imaging is illustrated with single shot flash radiographs obtained using low laser pulse energy. These results will enable the deployment of brighter laser driven x-ray sources at both compact and large laser facilities.

Equation of state of a dense plasma: Analytical results on the basis of quantum pair interaction potentials in the random phase approximation

In this work, using recently obtained expansion of the dielectric function in the long wave length limit by Moldabekov et al (2015 Phys. Plasmas 22 102104), we extended previously obtained formulas for the equation of state of the semiclassical dense plasma from Ramazanov et al (2015 Phys. Rev. E 92 023104) to the quantum case. Inner energy and contribution to the pressure due to plasma non-ideality derived for both Coulomb pair interaction and quantum pair interaction potentials. Obtained analytical result for the equation of state reproduces the Montroll-Ward contribution, which corresponds to the quantum ring sum. It was shown that the obtained results are consistent with the Thomas-Fermi approximation with the first order gradient correction. Additionally, the generalization of the quantum Deutsch potential to the case of the degenerate electrons is discussed. Obtained results will be useful for understanding of the physics of dense plasmas as well as for further development of the dense plasma simulation on the basis of the quantum potentials.

Status and Perspectives for P̄ANDA at FAIR

The Facility for Antiproton and Ion Research (FAIR) is an international accelerator facility which will use antiprotons and ions to perform research in the fields of nuclear, hadron and particle physics, atomic and anti-matter physics, high density plasma physics and applications in condensed matter physics, biology and the bio-medical sciences. It is situated in Darmstadt (Germany) and it is under construction. Among all projects in development at FAIR in this moment, this report focuses on the P̄ANDA experiment (antiProton ANnihilation at DArmstadt). Some topics from the Charm and Charmonium physics program of the P̄ANDA experiment will be highlighted, where P̄ANDA is expected to provide first measurements and original contributions, such as the measurement of the width of very narrow states and the measurements of high spin particles, nowaday undetected. The technique to measure the width of these very narrow states will be presented, and a general overview of the machine is provided.

Study of the heavy ion bunch compression in CSRm

The feasibility of attaining nanosecond pulse length heavy ion beam is studied in the main ring (CSRm) of the Heavy Ion Research Facility in Lanzhou. Such heavy ion beam can be produced by non-adiabatic compression, and it is implemented by a fast rotation in the longitudinal phase space. In this paper, the possible beam parameters during longitudinal bunch compression are studied with the envelope model and Particle in Cell simulation, and the results are compared. The result shows that the short bunch 238U28+ with the pulse duration of about 50 ns at the energy of 200 MeV/u can be obtained which can satisfy the research of high density plasma physics experiment.

MA-core loaded untuned RF compression cavity for HIRFL-CSR

Abstract To meet the requirements of high energy density physics and plasma physics research at HIRFL-CSR the goal of achieving a higher accelerating gap voltage was proposed. Therefore, a magnetic alloy (MA)-core loaded radio frequency (RF) cavity that can provide a higher accelerating gap voltage compared to standard ferrite loaded cavities has been studied at IMP. In order to select the proper magnetic alloy material to load the RF compression cavity, measurements of four different kinds of sample MA-cores have been carried out. By testing the small cores, the core composition was selected to obtain the desired performance. According to the theoretical calculation and simulation, which show reasonable consistency for the MA-core loaded cavity, the desired performance can be achieved. Finally about 1000 kW power will be needed to meet the requirements of 50 kV accelerating gap voltage by calculation.

An untuned MA-loaded cavity for HIRFL-CSR

In order to realize high energy density physics and plasma physics research at HIRFL-CSR, a magnetic alloy (MA)-loaded cavity has been studied. According to the theoretical calculation and simulation for the MA-loaded cavity, we achieved a better result. The MA-loaded cavity had a higher μQf value, with a higher shunt impedance and a higher accelerating gradient. The accelerating gradient was about 95 kV/m at 1.8003 MHz, 130 kV/m at 0.9000 MHz. Compared with the ferrite-loaded cavities that are used at HIRFL-CSR, with about 10 kV/m accelerating gradient, the MA-loaded cavity obviously has an advantage. The results of the theoretical calculation and the simulation, which meet the design requirements are in good agreement.

Pulsed Power System for the Orion High Power Laser

This paper describes the design and testing of the pulsed power system for the Orion Laser, which will be used for high temperature and density plasma physics research. The system supplies 8 MJ of energy to laser amplifiers and Faraday rotators. It consists of 17 capacitor bank modules, each with up to sixteen 150 μF charge storage capacitors, 25 kV power supply and controls. The energy is delivered by spark-gap switches to give a pre-pulse to ionise the flashlamps and a main pulse of 490 μs. The system delivers 5 shots a day with less than 0.2% variation in charge voltage.

Frontiers of the physics of dense plasmas and planetary interiors: Experiments, theory, and applications

Recent developments of dynamic x-ray characterization experiments of dense matter are reviewed, with particular emphasis on conditions relevant to interiors of terrestrial and gas giant planets. These studies include characterization of compressed states of matter in light elements by x-ray scattering and imaging of shocked iron by radiography. Several applications of this work are examined. These include the structure of massive “super-Earth” terrestrial planets around other stars, the 40 known extrasolar gas giants with measured masses and radii, and Jupiter itself, which serves as the benchmark for giant planets.

Warm Dense Matter and Strongly Coupled Plasmas Created by Intense Heavy Ion Beams and XUV-Free Electron Laser: An Overview of Spectroscopic Methods

High density plasma physics, radiation emission/scattering and related atomic physics, spectroscopy and diagnostics are going to make large steps forward due to new experimental facilities providing beams of intense heavy ions and X/XUV free electron laser radiation. These facilities are currently being established at GSI-Darmstadt and DESY-Hamburg in Germany to access new and complementary parameter regimes for basic research which have never been obtained in laboratories so far: homogenous benchmark samples near solid density and temperatures from eV up to keV. This will provide important impact to many disciplines like astrophysics, atomic physics in dense environments, dense and strongly coupled plasma effects, radiation emission, equation of state. The spectroscopic analysis of the radiation emission plays a key role in this research to investigate the dynamics of electric fields in multi-particle coupled Coulomb systems and the modification of plasma statistics.

Future Facility: FAIR at GSI

The Facility for Antiproton and Ion Research, FAIR, is a new particle accelerator facility to be built at the GSI site in Germany. The research at FAIR will cover a wide range of topics in nuclear and hadron physics, high density plasma and atomic physics, and applications in condensed matter physics and biology. A 1.1 km circumference double ring of rapidly cycling 100 and 300 Tm synchrotrons, will be FAIR's central accelerator system. It will be used to produce, inter alia , high intensity secondary beams of antiprotons and short-lived radioactive nuclei. A subsequent suite of cooler and storage rings will deliver heavy ion and antiproton beams of unprecedented quality. Large experiments are presently being designed by the NUSTAR, PANDA, PAX, CBM, SPARC, FLAIR, HEDgeHOB and BIOMAT collaborations.

Review of the 4th NLTE Code Comparison Workshop

We review the critical results of the 4th Non-LTE Code Comparison Workshop held in December 2005. To test the NLTE population kinetics codes, both steady-state and time-dependent cases for C, Ar, Fe, Sn, Xe, and Au plasmas were selected for detailed comparisons. Additional features such as the effects of non-Maxwellian free electrons, the influence of a Planckian radiation field, and the emission spectra were required in specific cases. The scope of problems was expanded from the previous workshops to include two problems outside the dense plasma physics, namely, the EUV lithography sources and the astrophysical photoionized plasmas. We briefly outline the technical organization of the workshop, present motivations for the chosen cases, and discuss some representative results.

Bent Marshak waves

Radiation-driven heat waves (Marshak waves) are ubiquitous in astrophysics and terrestrial laser-driven high-energy density plasma physics experiments. Generally, the equations describing Marshak waves are so nonlinear, that solutions involving more than one spatial dimension require simulation. However, in this paper it is shown that one may analytically solve the problem of the two-dimensional nonlinear evolution of a Marshak wave, bounded by lossy walls, using an asymptotic expansion in a parameter related to the wall albedo and a simplification of the heat front equation of motion. Three parameters determine the nonlinear evolution: a modified Markshak diffusion constant, a smallness parameter related to the wall albedo, and the spacing of the walls. The final nonlinear solution shows that the Marshak wave will be both slowed and bent by the nonideal boundary. In the limit of a perfect boundary, the solution recovers the original diffusion-like solution of Marshak. The analytic solution will be compared to a limited set of simulation results and experimental data.

Particle accelerator physics and technology for high energy density physics research

Interaction phenomena of intense ion- and laser radiation with matter have a large range of application in different fields of science, extending from basic research of plasma properties to applications in energy science, especially in inertial fusion. The heavy ion synchrotron at GSI now routinely delivers intense uranium beams that deposit about 1 kJ/g of specific energy in solid matter, e.g. solid lead. Our simulations show that the new accelerator complex FAIR (Facility for Antiproton and Ion Research) at GSI as well as beams from the CERN large hadron collider (LHC) will vastly extend the accessible parameter range for high energy density states. A natural example of hot dense plasma is provided by our neighbouring star the sun, and allows a deep insight into the physics of fusion, the properties of matter at high energy density, and is moreover an excellent laboratory for astroparticle physics. As such the sun's interior plasma can even be used to probe the existence of novel particles and dark matter candidates. We present an overview on recent results and developments of dense plasma physics addressed with heavy ion and laser beams combined with accelerator- and nuclear physics technology.