Increase In Plasma Energy Research Articles

Core‐SOL simulations of high‐power JET‐ILW pulses fuelled with gas and/or with pellets

AbstractExperimental analysis of two couples of pulses in the range of input power of 26–32 MW, shows that addition of pellet throughput to high gas dosing pulses does not modify the plasma energy, but leads to better conditions as far as the tungsten concentration and core radiation are concerned. Significantly decreasing the gas dosing with addition of high pellet throughput causes the increase of plasma energy, but the W concentration increases from 5.2 × 10−5 to 6.9 × 10−5 and the core radiation from 7.5 to 11 MW. From the numerical results of the self‐consistent core‐SOL COREDIV code two mechanisms appear to be responsible for the observed different W concentrations: the core residence time of W, which is related to the energy and particle confinement time, and the divertor impurity screening efficiency, dependent on the electron density and on the perpendicular transport coefficient in the SOL.

Preparation and synthesis of carbon nanomaterials from 1-hexanol by solution plasma process with Ar/O2 gas bubbles

This study presents the simple and catalyst-free methods for synthesizing carbon nanomaterials from 1-hexanol alcohol by using stable solution plasma process by varying the argon (Ar), oxygen (O2), and Ar and O2 mixtures plasma working gas bubble. The structural characteristics of carbon nanomaterials are measured by transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. The discharge characteristics are examined based on the discharge voltage, current, and optical emission spectrometer (OES) techniques. By using the external Ar gas bubble discharge during solution plasma process, the size of carbon nanoparticle and discharge voltage are decreased compared to the no gas case and the discharge current is increased, which would be due to the increase of plasma energy and enhancement of the square of plasma-liquid contact to plasma volume. By using the external O2 gas bubble discharge during solution plasma process, whereas, the size of carbon nanoparticle is increased compared to the no gas case and the discharge voltage and current are decreased, which would be due to the production of relatively high amounts of oxygen radicals, resulting in the flame synthesis. Raman spectra results show that the degree of graphitization of the carbon nanomaterials synthesized with external Ar 150 and O2 50 standard cubic centimeter per minutes (sccm) mixtures gas bubble during solution plasma process is observed to be greater than that of the carbon nanomaterials synthesized with the only Ar or O2 gas bubble. This solution plasma process by varying the plasma working gas mixtures can potentially be used for the precise nanomaterial synthesis.

Temporal-stability of plasma functionalized vertical graphene electrodes for charge storage

Vertical graphene is an emerging material for supercapacitor applications. Yet, its inherent hydrophobic nature restricts the interaction with electrolyte ions, which brings in high demand for developing hydrophilic vertical graphene surfaces. Herein, super-wetting vertical graphene nanosheets are achieved by an in-situ post-deposition oxygen plasma treatment. The plasma-treated vertical graphene nanosheets electrodes found to exhibit a ten-fold enhancement in specific capacitance. However, the super-wetting nature of the plasma-treated vertical graphene nanosheets transformed back to hydrophobic upon exposure to ambient conditions, yet the rate of transformation is governed by the plasma parameters in-turn the type of oxygen functional group attached. Noteworthy, the analogous effect is persisted in supercapacitor performance too. Furthermore, a correlation between the temporal-stability of wetting nature and supercapacitor performance is established; by measuring the charge storage capacity of vertical graphene surfaces with different water contact angle. A preferential shift in dominant oxygen functionalities from carboxyl type to hydroxyl and carbonyl type with an increase in plasma energy is evident. A symmetric coin-type electrochemical capacitor device using super-wetting vertical graphene nanosheets electrodes is fabricated and demonstrated its performance.

A new method for measuring plasma energy using superconducting helical coils

We proposed a new method for measuring plasma energy using superconducting helical field coil (HFC) signals. The change in HFC flux is experimentally confirmed due to the increase in plasma energy. The VMEC-DIAGNO equilibrium analysis code clarified the relation between the HFC flux change and the plasma energy increase, and the scaling law for the plasma energy measurement is obtained. The comparison between this proposed method and the conventional diamagnetic coil measurement has been carried out, and the effectiveness of this proposed technique using HFC is confirmed.

GDT Device. Recent Results and Future Plans for GDT Upgrade

GDT experiments of significance to a GDT-based neutron source development are reported in the areas of generation of axially peaked neutron flux profile, stable confinement with on-axis plasma beta ~ 40%, and radial electric field control. Skew injection of 4MW 15-17keV deuterium neutral beams into central cell resulted in generation of strongly peaked axial profile of neutron flux density. This can be described by a model of fast ion relaxation, which involves only classical mechanisms of electron drag and binary ion-ion collisions. Experiments with the radial limiter biasing show that the plasma density profile and radial losses respond to the electric filed profile. An increase of plasma energy was achieved with increased magnetic field in the central cell and optimized radial profile of electric field in the plasma. In these regimes of improved target plasma confinement, the on-axis plasma beta near the turning points of fast deuterons exceeded, as above mentioned, ~40%. The plans for future upgrade of the GDT device are discussed. It suggests considerable increase of NB injected power (up to 10MW) and extension of the pulse duration from 1ms to 3-5ms. After the upgrade, a significant increase of the electron temperature to 250-300eV could be obtained. Properties of the plasma with the parameters approaching those in the full-scale neutron source are planned to study in experiments with NB injection into additional cell near the end mirror.

Functionally Graded Plasma Spraying of Bio-Ceramics on Model Material of Implant.

The necessity to substitute the artificial part so called medical implant for broken or worn bone is growing as old people increase. Materials for implant should have both the same mechanical properties as original tissues and biocompatibility. However, it is difficult that a single material satisfies these requirements simultaneously. In this study, a hybrid implant material which was composed of surface material and substantial material was developed by plasma spraying technique. Powders of hydroxyapatite (HAp) and titanium were sprayed on the titanium substrate in such way that the composition of HAp was increased gradually toward the surface. The performance of obtained HAp coatings was investigated with SEM observation, X-ray diffraction, adherence test, friction test and dissolution test. It was found that hardness, adhesion strength and corrosion resistance were improved with increase in plasma energy and that they were much improved by YAG laser irradiation after spraying. However, sprayed coatings were inferior in hardness and corrosion resistance to the pig bone or sintered HAp because of porous structure. Therefore to produce medical implants by this method, biomimetic designing will be necessary.

Energy characteristics of an explosively driven plasma compressor

Two basic parameters affect the energy characteristics of an explosively driven plasma compressor: the fill density and the ratio of the mass of explosive to the plate mass. Despite the increase in plasma energy, as the filling density in the compression chamber is increased, the specific energy of the plasma decreases due to the arrival of impurities from the chamber walls. In order to obtain high compressor efficiencies, it is necessary to increase the efficiency of energy transfer from the projectile plate to the plasma (η2) by choosing appropriate values of the operating parameters (rM and σ). The author thanks A. A. Deribas, A. E. Voitenko, and L. V. Al'tshuler for discussing these results and for valuable comments and V. Yu. Afonin for help in doing the experiments.