Liner Plasma Research Articles

The astrophysical S-factor for dd-reactions at keV-energy range

Abstract The experimental results of measurements of the astrophysical S-factor for dd-reaction at keV-energy range collision energies using liner plasma technique are presented. The experiments were carried out at the high current generator of the Institute of High-Current Electronics in Tomsk, Russia. The measured values of the S-factors for the deuteron collision energies 1.80, 2.06 and 227 keV are S d d = ( 114 ± 68 ) , ( 64 ± 30 ) , ( 53 ± 16 ) b ⋅ k e V , ${{S}_{dd}}=(114\pm 68),(64\pm 30),(53\pm 16)b\cdot keV,$ respectively. The corresponding cross sections for dd-reactions, described as a product of the barrier factor and measured astrophysical S-factor, are σ d d n ( E c o l = 1.80 keV ) = ( 4.3 ± 2.6 ) . $\sigma _{dd}^{n}\left( {{E}_{col}}=1.80\text{keV} \right)=(4.3\pm 2.6).$ 10 − 33 c m 2 ; σ d d n ( E c o l = 2.06 keV ) = ( 9.8 ± 4.6 ) ⋅ 10 − 33 c m 2 ; σ d d n ( E c o l = ${{10}^{-33}}~c{{m}^{2}};\sigma _{dd}^{n}\left( {{E}_{col}}=2.06\text{keV} \right)=(9.8\pm 4.6)\cdot {{10}^{-33}}~c{{m}^{\text{2}}};\sigma _{dd}^{n}\left( {{E}_{col}}= \right.$

Effect of different liner techniques and argon plasma treatment of zirconia base on the adhesion and color change of veneering ceramic

This in vitro study aimed to investigate the bond strength and discoloration between the zirconia framework and veneer ceramic applied after liner and argon plasma treatment with two different techniques. A total of 200 zirconium substructures of 12 mm length, 10 mm width, and 0.7 mm thickness were divided into five subgroups for the application of different thicknesses of liner: C (no liner application), L1 (0.1 mm), L2 (0.2 mm), L3 (0.1 mm + 0.1 mm) and LA (0.1 mm + 0.1 mm + argon plasma). The zirconia substructures were fabricated by two different techniques (A: layering, B: press-on). The specimens of the three subgroups Control, Group L3, and Group LA were tested for color difference. Color parameters were measured using a spectrophotometer before and after thermal cycling, and differences (CIEDE 2000 [ΔE00]) were calculated. The shear bond strength was applied to all subgroups using a universal testing machine. The data were analyzed statistically using the Shapiro–Wilk, Levene, and Kruskal–Wallis tests. The interface and fractured surfaces of the specimens were also evaluated by scanning electron microscopy (SEM). Significant differences were found between the groups (p < 0.05) in terms of shear bond strength and color differences (p < 0.001). Group LA showed significantly higher bond strength and color stability than the other groups (p < 0.001). The results of the study demonstrated that the application of liner and argon plasma between the upper and lower structures of all-ceramic systems significantly affects the bond strength and final colour of the restorations.

Study of the Compression Dynamics of a Fiber Liner with a Deuterated Target Mounted on the Axis

Compression of a fiber array with a deuterated target mounted on its axis is studied at the Angara-5-1 facility (3.5 MA, 100 ns). Cylindrical arrays with an initial diameter of 12 mm made from polypropylene fibers with a diameter of 13.4 µm are used. The number of fibers varied from 30 to 120. The target with the density of 0.08–0.2 g/cm3 and the diameter of 1 mm was made on the basis of deuterated polyethylene. A 10‑frame ultra-high-speed X-ray camera, optical slit scans, an integral X-ray pinhole camera, vacuum X-ray diodes, a crystal spectrograph, and neutron detectors are used to measure the plasma parameters in the Z‑pinch. It is found that the dynamics of plasma compression and evolution of local plasma formations, which are sources of neutrons and soft X-ray emission in the energy range of E > 150 eV, depend on the load configuration: the number of fibers, diameter, and density of the deuterated target. Efficient compression of the liner plasma, high concentration and temperature of the compressed target state, as well as the highest neutron yield (8 × 109 neutron/pulse) are observed in experiments with arrays with the fiber number of 60, inside which the target with the diameter of 1 mm and density of 0.2 g/cm3 was placed. The electron density and temperature of the hot plasma in local formations are estimated as ne ≈ 1021 cm–3, Te ≈ 1 keV, respectively. The average neutron energy was 2.6 ± 0.2 MeV. The intensity of the plasma formation $$\dot {m}$$ [in µg/(cm2 ns)] of polypropylene fibers under the action of the discharge current of the facility is determined in experiments with fiber arrays.

Optimization of cylinder liner plasma spraying mode

At present one of the most promising methods to remanufacture worn-out machine parts is plasma spraying. The paper describes the selection of the optimum plasma spraying technique to coat the worn-out wall surface of the diesel engine cylinder liners. All the data have been MathCad processed and the regression models equivalent to the algoristic-type model of plasma spraying have been developed. The experiments have resulted in achieving the optimization parameters, the mean value of which is presented in the paper. The given plasma spraying mode allows one not only to remanufacture the worn-out wall surface of the diesel engine cylinder liners but also to obtain the best coating properties.

Irradiation effects of hydrogen and helium plasma on different grade tungsten materials

Fine-grain tungsten alloys could be one of the solutions for the plasma facing materials of future DEMO reactors. In order to evaluate the service performances of the newly developed W alloys under edge plasma irradiation and the synergetic effect of fusion plasma together with high heat flux, both low energy He ions and high energy H, H/He mixed neutral beam irradiation on W-ZrC, W-K, W-Y2O3, W-La2O3 and CVD-W coating were performed respectively at a liner plasma facility (Dalian Nationality University, China) and the neutral beam facility GLADIS (IPP, Germany). Surface damages were characterized, and the crack formation and extension behaviors under ELM-like transient loading after H and H/He mixed beam irradiation were also investigated in the 60kW EMS-60 facility (Electron beam Materials testing Scenario) at SWIP (Southwestern Institute of Physics, China). The experimental results indicated that surface damages induced by low or high energy H/He ion/neutral beam didn't closely correlate with the type of tungsten materials. However, H/He (6at% He concentration) neutral beam induced more significant surface damages of the tested W materials than only H neutral beam irradiation under the similar irradiation conditions. Similarly, the mixed H/He pre-exposure remarkably reduced the critical power of crack initiation compared with the un-irradiated samples under 100 repetitive loads of 1ms pulse, while no significant degeneration for the case of only H beam irradiation was observed.

Observation and particle simulation of vaporized W, Mo, and Be in PISCES-B plasma for vapor-shielding studies

Interactions of Tungsten (W), Molybdenum (Mo), and Beryllium (Be) vapors with a steady-state plasma were studied by the PISCES-B liner plasma experiments as well as Particle-In-Cell (PIC) simulations for the understanding of vapor-shielding phenomena. Effective cooling of the plasma by laser-generated Be vapor was observed in PISCES-B. On the other hand, no apparent cooling was observed for W and Mo vapors. The PIC simulation explains these experimental observations of the difference between low-Z and high-Z vapors. Decrease of electron temperature due to the vapor ejection was observed in case of a simulation of the Be vapor. As for the W vapor, it was found that the plasma cooling is localized only near the wall at a higher electron density plasma (∼1019m−3). On the other hand, the appreciable plasma cooling can be observed in a lower density plasma (∼1018m−3) for the W vapor.

A fast time-response bolometer for soft X-ray radiation energy measurements in a high-current Z-pinch

A high-sensitivity bolometer with a short time response to heating with external radiation has been developed. It is intended for measuring the integral parameters of soft X-ray radiation of liner plasma. The bolometer is adapted to the conditions of explosion experiments with an increased level of electromagnetic pickups at facilities that are based on magnetic-explosion generators with megaampere currents. The bolometer has a metal casing for improving the noise immunity of measurements. A 2-μm-thick nickel foil is used as the material for the resistive element of the working substance of the bolometer. The choice of the material and the geometrical dimensions of the bolometer working elements were analyzed. The ultimate thermal load on the bolometer was determined. A technique for calibrating the working elements using a pulse current was developed. The working capacity, good noise immunity, and a high sensitivity of the bolometer were demonstrated in experiments. The dynamic range in measurements of the surface energy density of X rays is 0.03–0.3 J/cm2.

Gas-puff liner implosion in the configuration with helical current return rods

Results of experiments with double-shell gas-puff liners carried out on a high-current MIG generator (2 MA, 80 ns) are presented. To stabilize the process of liner implosion and increase the efficiency of energy transfer from the generator to the liner plasma, a current return in the form of a multifilar helix was used. The effect of the configuration of the current return on the parameters of the generated pulses of argon and neon K-shell radiation (with photon energies of 3–5 and 0.9–1.5 keV, respectively) and the neutron yield from a deuterium liner were studied.

High power pulse compression using magnetic flux compression

A design of high power pulse compression by (axial) magnetic flux compression is presented. Optimal model parameters are presented for liner plasma using the thin-shell model code and finite element analyses for stator coils design. Typical model simulation results indicated that a 1.5 μs rise-time pulse with 7.5 MA peak value could be compressed to 20 MA peak value fast rise pulse (∼40 ns rise-time) in the secondary circuit with a 0.5 Ω external load. The limitations resulting from Joule heating and extra high magnetic field diffusion on stator coils are discussed.

Assessing the 2ωpe instability and other preheat considerations in ignition-scale hohlraums

In recent experiments[1] Sean Regan, et. al. for the first time observed the 2ωpe instability from window plasma in hohlraum targets. This instability can also operate[2] at peak power near the edge of the inner beams in the ablator plasma and near the edge of the outer beams in the liner plasma. Fortunately only a small fraction of the laser energy was estimated to be at risk. A more quantitative assessment of the energy at risk at peak power will here be given. We show that the instability threshold can be significantly reduced for laser beams with an angle of incidence of about 60 degrees due to the swelling of the laser field near its turning point. A simple model is given. It is also shown that for frequently cited plasma conditions, the Raman-scattered light wave can itself drive the 2ωpeinstability. This effect is relevant for the nonlinear saturation of stimulated Raman scattering (SRS) and the resulting heated electron generation. Some estimates are given. Finally we conclude with a few remarks about hot electron preheat.

High-Magnetic-Field Generation by Magnetic Flux Compression in Imploding Plasma Liners

The MIG generator was used in a magnetic flux compression experiment to produce a high magnetic field inside a dielectric tube located along the axis of an imploding plasma liner. With a liner current of ~ 1 MA and a tube diameter of 2-5 mm, magnetic fields of up to 60 T with a quasi-steady pulse duration of 100 ns and more were produced. The high magnetic field region is protected from the liner plasma and radiation by the tube wall, and it can be used to study the physical phenomena that occur in high and ultrahigh magnetic fields. The physical processes responsible for the evolution of the magnetic field in a dielectric tube are discussed.

Spherical cauliflower-like carbon dust formed by interaction between deuterium plasma and graphite target and its internal structure

Simulated experiments to produce carbon dust particles with cauliflower structure have been performed in a liner plasma device, NAGDIS-II by exposing high density deuterium plasma to a graphite sample (IG-430U). Formation of carbon dust depends on the surface temperature and the incident ion energy. At a surface temperature 600–700 K, a lot of isolated spherical dust particles are observed on the graphite target. The internal structure of an isolated dust particle was observed with Focused Ion Beam (FIB) system and Transmission Electron Microscope (TEM) in detail. FIB analysis clearly shows there exist honey-combed cell structure with thin carbon walls in the dust particle and the dust particle grows from the graphite surface. TEM image also shows that the dust particle is made of amorphous carbon with crystallized grains with diameters of 10–50 nm.

High-current Z-pinch disintegration and the problem of peripheral equipment protection

The process of Z-pinch decay upon current termination is considered. The experimental data obtained for the Angara-5-1 facility on compression of multiwire tungsten liners are discussed. It is shown that among the decay products there are microparticles of the eroded liner construction material and plasma fluxes. It was determined that the plasma flow velocities exceeded the ‘thermal’ velocities of the Z-pinch plasma. A model for the description of the process of ion acceleration based on an ambipolar mechanism is suggested. Precautions for protection of the peripheral equipment against the decay products of Z-pinch are discussed and protective components are studied. A fast electromagnetic shutter is used for protection from microparticles.

Effect of liner non-uniformity on plasma instabilities in an inverseZ-pinch magnetized target fusion system: liner-on-plasma simulations and comparison with linear stability analysis

Two-dimensional (2D) magneto-hydrodynamic (MHD) liner-on-plasma computations have been performed to study the growth of instabilities in a magnetized target fusion system involving the cylindrical compression of an inverse Z-pinch target plasma by a metallic liner. The growth of modes in the plasma can be divided into two phases. During the first phase, the plasma continues to be Kadomtsev stable. The dominant mode in the liner instability is imposed upon the plasma in the form of a growing perturbation. This mode further transfers part of its energy to its harmonics. During the second phase, however, non-uniform implosion of the liner leads to axial variations in plasma quantities near the liner–plasma interface, such that certain regions of the plasma locally violate the Kadomtsev criteria. Further growth ofthe plasma modes is then due to plasma instability. The above numerical study has been complemented with a linear stability analysis for the plasma, the boundary conditions for this analysis being obtained from the liner-on-plasma simulation. The stability of axisymmetric modes in the first phase is found to satisfy the Kadomtsev condition Q0<1. Furthermore, the growth rates of these modes in the second phase are found to agree well with the predictions of the linear stability analysis. A linear stability analysis for m>1 modes, using equilibrium profiles from the 2D MHD study, shows that their growth rates can exceed those for m=0 by as much as an order of magnitude.

Liner-Driven Pulsed Magnetized Target Fusion Power Plant

Magnetized Target Fusion (MTF) occupies an intermediate region between conventional Magnetic Fusion Energy (MFE) and Inertial Fusion Energy (IFE). A particular approach, extrapolated from the ongoing FRX-L experimental effort, involves the generation of a Field Reversed Configuration (FRC) suitable for translation along an axial magnetic field and cylindricalliner (i.e., converging flux conserver) implosion and pdV heating to burn conditions. The fusion gain, Q (ratio of DT fusion yield to the sum of initial liner kinetic energy plus plasma formation energy), sets the pulsed power-plant duty cycle. The modular power-plant embodiment recalls the Fast Liner Reactor (FLR) and shares stand-off and blast-mitigation features of the recent characterization of the Z-IFE. Recycle and economic remanufacture of destroyed front-end apparatus must be performed under tight cost constraints. A tin-lithium alloy is being investigated for multifunctional suitability as the liner, transmission-line, and primary coolant/breeder material. Key performance drivers are described.

Perspectives on Magnetized Target Fusion Power Plants

One approach to Magnetized Target Fusion (MTF) builds upon the ongoing experimental effort (FRX-L) to generate a Field Reversed Configuration (FRC) target plasma suitable for translation and cylindrical-liner (i.e., converging flux conserver) implosion. Numerical modeling is underway to elucidate key performance drivers for possible future power-plant extrapolations. The fusion gain, Q (ratio of DT fusion yield to the sum of initial liner kinetic energy plus plasma formation energy), sets the power-plant duty cycle for a nominal design electric power [e.g. 1,000 MWe(net)]. A pulsed MTF power plant of this type derives from the historic Fast Liner Reactor (FLR) concept and shares attributes with the recent Inertial Fusion Energy (IFE) Z-pinch and laser-driven pellet HYLIFE-II conceptual designs.

Study of the pd reaction at ultralow energies using hydrogen liner plasma

The pd reaction (pd → He + γ (5.5 MeV)) is studied in the astrophysical energy collision range of protons with deuterons using the hydrogen liner in the inverse Z-pinch configuration at the pulsed power generator MIG (HCEI, Tomsk). Fundamental characteristics of this and other light-nucleus reactions at ultralow energies are important for problems of basic physics and astrophysics. The knowledge of the energy distribution of the nuclei participating in these reactions is important due to their exponential type of dependence on the collision energy. Two experimental techniques were designed and tested for recovering the energy distribution of liner protons incident on the CD2 target by using optical detectors and ion collectors. It is shown that the combined use of these two techniques could provide relevant information on the energy distribution of the accelerated protons in the liner. The estimates of the upper limits for the astrophysical S factor and effective cross section of the pd reaction in the proton-deuteron collision energy range of 2.7–16.7 keV are obtained: \(\bar S_{pd} (E_{pd} = 10.2 keV) \leqslant 2.5 \times 10^{ - 7} MeV b;\overline \sigma _{pd} (2.7 \leqslant E_{pd} \leqslant 16.7 keV) \leqslant 4 \times 10^{ - 33} cm^2 \).

X-ray backlighting of the axial region of a multiwire liner plasma in the angara-5-1 facility

Results are presented from experiments on the X-ray backlighting of the axial region of an imploding high-current multiwire liner. Backlighting was performed with the use of an X-pinch serving as a source of soft X-ray emission, which was recorded by pin diodes. The use of several filters with different passbands in front of the pin diodes allowed the interpretation of the results of measurements in experiments with cascade composite liners. The sensitivity of the diagnostics was ≈125 µg/cm2 for a plasma of high-Z elements (W) and ≈220 µg/cm2 for a plasma of low-Z elements (C, O, N) at a photon energy of the probing radiation of 1.0–1.5 keV. An advantage of the method is its high time resolution (≈1 ns) and the possibility of the separation in time of the emission bursts from Z-and X-pinches on the liner axis. The method does not impose restrictions on the pulse duration of the backlighting radiation source.

Deuterium liner and multiparametric studies of the formation of an inverse Z-pinch

A method and results of measurements are presented of the ion energy distribution in a deuterium liner accelerated in the inverse Z-pinch, in which the plasma is accelerated electrodynamically from the liner axis. Knowledge of the deuteron energy distribution is of primary importance for the correct interpretation of the experimental results from the study of the dd-reaction in the range of infralow energies with the use of a liner plasma. Experiments were carried out in a high-current pulsed accelerator (I=950 kA, τ=80 ns) at the Institute of High-Current Electronics of the Siberian Division of the Russian Academy of Sciences (Tomsk, Russia). In the initial state, the liner is a supersonic hollow deuterium jet 32 mm in diameter and 20 mm in length. The liner parameters were measured with the help of optical detectors of H α and H β deuterium lines and magnetic probes arranged in a radial direction (along the direction the liner expansion). In addition, scintillation spectrometers and BF3 counters were used to measure the intensity of the neutron flux produced in the d + d → 3He + n reaction. The results obtained by simultaneously analyzing the data from magnetic probes, optical detectors, and neutron detectors point to the possibility of using a rather simple method for measuring the parameters of the liner accelerated up to energies of 3–6 keV.

LiF detectors application for detection of X-ray radiation from plasma

Abstract The LiF detectors of a commercial device with the measurement range from 25 keV to 1.3 MeV were successfully used for of the monitoring X-ray from the imploding liner plasma on the high current pulse generator S-300. The detector readings were discovered to decrease more than ten times behind a thin lavsan filter of 2 μm thick in comparison with the open detector readings. This result demonstrates a possibility of using the LiF detector for registration of soft X-ray less than 1 keV. The detectors work in the regime of fuli absorption of the incident X-ray radiation up to the energy of about 10 keV. The stability of the detector readings under identical experimental conditions allows one to use them for integral monitoring of the X-ray plasma radiation.