Search results for "plasma diagnostics"
showing 10 items of 59 documents
Diagnostics for studies of novel laser ion acceleration mechanisms.
2014
Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel accelera…
The effect of rf pulse pattern on bremsstrahlung and ion current time evolution of an ECRIS.
2010
Time-resolved helium ion production and bremsstrahlung emission from JYFL 14 GHz ECRIS is presented with different radio frequency pulse lengths. rf on times are varied from 5 to 50 ms and rf off times from 10 to 1000 ms between different measurement sets. It is observed that the plasma breakdown occurs a few milliseconds after launching the rf power into the plasma chamber, and in the beginning of the rf pulses a preglow transient is seen. During this transient the ion beam currents are increased by several factors compared to a steady state situation. By adjusting the rf pulse separation the maximum ion beam currents can be maintained during the so-called preglow regime while the amount o…
Laser plasma plume structure and dynamics in the ambient air: The early stage of expansion
2011
Laser ablation plasma plume expanding into the ambient atmosphere may be an efficient way to produce nanoparticles. From that reason it would be interesting to study the properties of these laser induced plasmas formed under conditions that are known to be favorable for nanoparticles production. In general, plume behavior can be described as a two-stage process: a “violent” plume expansion due to the absorption of the laser beam energy (during the laser pulse) followed by a fast adiabatic expansion in the ambient gas (after the end of the laser pulse). Plasma plume may last a few microseconds and may have densities 10−6 times lower than the solid densities at temperatures close to the ambie…
Tracer-Encapsulated Solid Pellet (TESPEL) injection system for the TJ-II stellarator
2016
A tracer-encapsulated solid pellet (TESPEL) injection system for the TJ-II stellarator was recently developed. In order to reduce the time and cost for the development, we combined a TESPEL injector provided by National Institute for Fusion Science with an existing TJ-II cryogenic pellet injection system. Consequently, the TESPEL injection into the TJ-II plasma was successfully achieved, which was confirmed by several pellet diagnostics including a normal-incidence spectrometer for monitoring a tracer impurity behavior.
In situ monitoring of pulsed laser indium–tin-oxide film deposition by optical emission spectroscopy
2001
We performed optical emission spectroscopy to monitor the plasma produced during the ablation of indium-tin-oxide targets under different oxygen pressure conditions using a pulsed UV laser. Molecular bands of InO were identified in the fluorescent spectra produced by pulsed laser ablation. InO line monitoring allowed obtaining the optimal conditions for good-quality ITO film deposition. We demonstrated that it is possible to correlate InO line spectroscopic parameters with the conditions required to fabricate a high-conductivity and high-transparent ITO thin film. In particular, low resistivity (10-4 to 10-3 Ω cm) was obtained in films deposited at room temperature by regulating oxygen pres…
Effects of the process conditions on the plume of a laser-irradiated indium–tin-oxide target
2001
Abstract The plume of a laser-ablated indium–tin-oxide target was investigated by optical emission spectroscopy. Atomic and ionic species of indium, tin and oxygen were observed; moreover, molecular bands of indium oxide were identified in the fluorescent spectra. The effects of the oxygen as a background gas and of the laser fluence on the behaviour of the ejected particles were studied with respect to the intensity of the emission and the delay time as a function of the observation distance from the target surface. The non-linear behaviour of the fluorescent species with the process conditions could infer spatial variations of the plume composition. The analysis demonstrates a plume expan…
Spectroscopic method to study low charge state ion and cold electron population in ECRIS plasma
2018
The results of optical emission spectroscopy experiments probing the cold electron population of a 14 GHz Electron Cyclotron Resonance Ion Source (ECRIS) are reported. The study has been conducted with a high resolution spectrometer and data acquisition setup developed specifically for the diagnostics of weak emission line characteristic to ECRIS plasmas. The optical emission lines of low charge state ions and neutral atoms of neon have been measured and analyzed with the line-ratio method. The aforementioned electron population temperature of the cold electron population (Te < 100 eV) is determined for Maxwell-Boltzmann and Druyvesteyn energy distributions to demonstrate the applicability …
On the Secondary Discharge of an Atmospheric-Pressure Pulsed DBD in He with Impurities
2008
The secondary discharge was induced at the end of a slow-falling voltage flank, when a semisine monopolar pulse voltage excites the dielectric-barrier discharge. Formation and properties of the secondary discharge with respect to different dielectric materials such as glass, ceramic, and polyethylene theraphtalate were studied. The tunable diode laser absorption spectrometry (at 777.194 nm) was used to analyze the time-space distribution of the density of the atomic oxygen in metastable state (35S2 rarr 35P3) in addition to both discharge voltage and discharge current versus time. The secondary discharge is always formed, and its amplitude, as well as the amplitude of the main discharge, de…
Spatial and Spectral Distributions of the Hydrogen $\hbox{H}_{\alpha}$ Line in Dielectric-Barrier Discharges
2008
It is shown that the optical emission method, based on measured spatial and spectral distributions of the Halpha radiation, provides valuable information on physical conditions in the volume of dielectric-barrier discharges. In the case when the registration allows the determination of light polarization, the measured spectra may provide information about the distribution of the electric-field strength in a direction that is perpendicular to the surfaces limiting the discharge volume. Visualization of the experimental data of spatial distributions of the hydrogen Halpha line is presented.
PROMINENCE PLASMA DIAGNOSTICS THROUGH EXTREME-ULTRAVIOLET ABSORPTION
2013
In this paper we introduce a new diagnostic technique that uses prominence EUV and UV absorption to determine the prominence plasma electron temperature and column emission measure, as well as He/H relative abundance; if a realistic assumption on the geometry of the absorbing plasma can be made, this technique can also yield the absorbing plasma electron density. This technique capitalizes on the absorption properties of Hydrogen and Helium at different wavelength ranges and temperature regimes. Several cases where this technique can be successfully applied are described. This technique works best when prominence plasmas are hotter than 15,000 K and thus it is ideally suited for rapidly hea…