Search results for "asma"

Characteristic Kα emission of electron cyclotron resonance ion source plasmas

2018

This thesis presents the results of an investigation of the volumetric Kα emission rate/inner shell ionization rate from an Electron Cyclotron Resonance Ion Source (ECRIS) plasma tuned predominantly for high charge state ion production. The experimental work include four complimentary studies covering the influence of a parametric sweep of the four source tune parameters i.e microwave power, neutral gas flow, biased disc voltage and magnetic field on the volumetric Kα emission rate, an investigation into the gas mixing effect, an investigation into the effectiveness of double-frequency heating mode and finally an investigation into microwave induced electron losses (relative and direct) from th…

A novel approach to β-decay: PANDORA, a new experimental setup for future in-plasma measurements

2022

International audience; Theoretical predictions as well as experiments performed at storage rings have shown that the lifetimes of β-radionuclides can change significantly as a function of the ionization state. In this paper we describe an innovative approach, based on the use of a compact plasma trap to emulate selected stellar-like conditions. It has been proposed within the PANDORA project (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) with the aim to measure, for the first time in plasma, nuclear β-decay rates of radionuclides involved in nuclear-astrophysics processes. To achieve this task, a compact magnetic plasma trap has been designed…

Biocompatibility and Antibacterial Properties of ZnO-Incorporated Anodic Oxide Coatings on TiZrNb Alloy

2020

In a present paper, we demonstrate novel approach to form ceramic coatings with incorporated ZnO nanoparticles (NPs) on low modulus TiZrNb alloy with enhanced biocompatibility and antibacterial parameters. Plasma Electrolytic Oxidation (PEO) was used to integrate ZnO nanoparticles (average size 12&ndash

Incorporation mechanism of colloidal TiO2 nanoparticles and their effect on properties of coatings grown on 7075 Al alloy from silicate-based solutio…

2021

Plasma electrolytic oxidation (PEO) was applied using a pulsed unipolar waveform to produce Al2O3-TiO2 composite coatings from sol electrolytic solutions containing colloidal TiO2 nanoparticles. The sol solutions were produced by dissolving 1, 3, and 5 g/L of potassium titanyl oxalate (PTO) in a silicate solution. Scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, and Raman spectroscopy were applied to characterizing the coatings. Corrosion behavior of the coatings was investigated using polarization and impedance techniques. The results indicated that TiO2 enters the coating through all types of micro-discharging and is doped into the alumina phase. The higher…

Effect of Molybdate on Corrosion Performance of Oxide Coating Produced on 7075 Al Alloy Using PEO

2022

In this research, plasma electrolytic oxidation (PEO) coatings were prepared on 7075 Al alloy in a silicate-based solution with Na2MoO4 additive using a unipolar waveform at constant current density. The coatings displayed micro-pores, micro-cracks, pancake-like and crater-like features, and also solidified molten oxide particles on the surface. The coatings were majorly composed of Al2O3 (γ, δ, and α), SiO2 (amorphous), and MoO3 phases, which confirms the incorporation of molybdenum in the case of additive-containing coatings. Molybdenum species were transported through cracks, channels, and micropores, as the ready access pathways into the coating and partly sealed the c…

Recent progress on the superconducting ion source VENUS.

2012

The 28 GHz Ion Source VENUS (versatile ECR for nuclear science) is back in operation after the superconducting sextupole leads were repaired and a fourth cryocooler was added. VENUS serves as an R&D device to explore the limits of electron cyclotron resonance source performance at 28 GHz with its 10 kW gryotron and optimum magnetic fields and as an ion source to increase the capabilities of the 88-Inch Cyclotron both for nuclear physics research and applications. The development and testing of ovens and sputtering techniques cover a wide range of applications. Recent experiments on bismuth demonstrated stable operation at 300 eμA of Bi31+, which is in the intensity range of interest for hig…

The electron cyclotron resonance ion source with arc-shaped coils concept

2012

The main limitation to further improve the performance of ECR ion sources is set by the magnet technology related to the multipole magnet field used for the closed minimum-B structure. The JYFL ion source group has sought different approaches to improve the strength of the minimum-B structure required for the production of highly charged ion beams. It was found out that such a configuration can be realized with arc shaped coils. The first prototype, electron cyclotron resonance ion source with arc-shaped coils (ARC-ECRIS), was constructed and tested at JYFL in 2006. It was confirmed that such an ion source can be used for the production of highly charged ion beams. Regardless of several cos…

Thermal Energy Density Driven Magnetic Reconnection

Magnetic reconnection is usually associated with conversion of magnetic energy into particle acceleration or thermal energy. However, a specific reconnection process driven by plasma pressure gradients was identified in Ref.[1] with a consistent theory of (non-ideal) MHD m0=1 modes in well confined plasmas. This process, based on an Ohm's law contribution to the electron balance equations, remains the basis for the explanation of the observed sawtooth oscillations of the central plasma pressure and for the inferred magnetic field structures due to fishbone oscillations associated with injected high energy particle populations. A novel process [2] expected to have a wide range of application…

Non-Thermal Fusion Burning Plasma Regimes

The Ignitor project is aimed at approaching ignition conditions in Deuterium-Tritium plasmas in order to investigate the issues related to the kind of characteristics of these plasmas, following the line of compact high field opened with the Alcator and Frascati Torus programs, which were capable of producing high density plasma regimes with record confinement properties combined with high degrees of plasma purity. We present a theoretical model describing the emergence of tridimensional structures in magnetically confined plasmas which can significantly change the conditions under which meaningful fusion burn conditions can be reached. These structures can be said to consist of "captive ba…

Effects of magnetic configuration on hot electrons in a minimum-B ECR plasma

2020

To investigate the hot electron population and the appearance of kinetic instabilities in highly charged electron cyclotron resonance ion source (ECRIS), the axially emitted bremsstrahlung spectra and microwave bursts emitted from ECRIS plasma were synchronously measured on SECRAL-II (Superconducting ECR ion source with Advanced design in Lanzhou No. II) ion source with various magnetic field configurations. The experimental results show that when the ratio of the minimum field to the resonance field (i.e. Bmin/Becr) is less than ~0.8, the bremsstrahlung spectral temperature Ts increases linearly with the Bmin/Becr–ratio when the injection, extraction and radial mirror fields are kept const…