Search results for "Physics::Plasma Physics"
showing 10 items of 247 documents
On the sensitivity of ion traps for spectroscopic applications
1979
Ba+ ions, created by surface ionization near one endcap of an rf quadrupole trap were slowed down by collisions with the background gas. At He pressures of 10−6 mbar or more 2% of the primary ions could be trapped. The sensitivity of ion detection by fluorescence radiation allows spectroscopic experiments, starting from less than 107 particles. The observation of the ground-state hyperfine splitting of137Ba+ is given as an example.
Photoelectron emission induced by low temperature hydrogen plasmas
2018
Experimental results of low temperature hydrogen plasma induced photoelectron emission measurements comparing two different plasma heating methods are summarized. By exposing the samples to the vacuum ultraviolet radiation of a filament-driven multi-cusp arc discharge ion source and a 2.45 GHz microwave-driven ion source, it has been measured that the total photoelectron emission from various metal surfaces is on the order of 1 A per kW of plasma heating power, which can be increased by a factor of 2–3.5 with a thin layer of alkali metal. The possible effects of the photoelectrons on the plasma sheath structure are studied with a 1D collisionless model extended to include the contribution o…
Study of Gasdynamic Electron Cyclotron Resonance Plasma Vacuum Ultraviolet Emission to Optimize Negative Hydrogen Ion Production Efficiency
2019
Negative hydrogen ion sources are used as injectors into accelerators and drive the neutral beam heating in ITER. Certain processes in low-temperature hydrogen plasmas are accompanied by the emission of vacuum ultraviolet (VUV) emission. Studying the VUV radiation therefore provides volumetric rates of plasma-chemical processes and plasma parameters. In the past we have used gasdynamic ECR discharge for volumetric negative ion production and investigated the dependencies between the extracted H$^-$ current density and various ion source parameters. It was shown that it is possible to reach up to 80 mA/cm$^2$ of negative ion current density with a two electrode extraction. We report experime…
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…
ECRIS plasma spectroscopy with a high resolution spectrometer
2020
Electron Cyclotron Resonance Ion Source (ECRIS) plasmas contain high-energy electrons and highly charged ions implying that only noninvasive methods such as optical emission spectroscopy are reliable in their characterization. A high-resolution spectrometer (10 pm FWHM at 632 nm) enabling the detection of weak emission lines has been developed at University of Jyväskylä, Department of Physics (JYFL) for this purpose. Diagnostics results probing the densities of ions, neutral atoms, and the temperature of the cold electron population in the JYFL 14 GHz ECRIS are described. For example, it has been observed that the cold electron temperature drops from 40 eV to 20 eV when the extraction volta…
The effect of microwave power on the Ar9+ and Ar13+ optical emission intensities and ion beam currents in ECRIS
2018
The production of Ar9+ and Ar13+ ions in an ECRIS plasma and the efficiency of the ion beam extraction and transport of the resulting Ar9+ and Ar13+ ion beams have been studied with the JYFL 14 GHz ECRIS by using optical emission spectroscopy and measurement of the m/q analyzed beam currents. The relative changes in both the optical emission and the ion beam current in CW mode as function of microwave power and in amplitude modulation (AM) operation mode are reported. The results indicate a discrepancy between the parametric dependence of high charge state ion densities in the core plasma and their extracted beam currents. The observation implies that in CW mode the ion currents could be li…
Time profile of ion pulses produced in a hot-cavity laser ion source.
2010
The time spreads of Mn ions produced by three-photon resonant ionization in a hot-cavity laser ion source are measured. A one-dimensional ion-transport model is developed to simulate the observed ion time structures. Assuming ions are generated with a Maxwellian velocity distribution and are guided by an axial electric field, the predictions of the model agree reasonably well with the experimental data and suggest that the ions are radially confined in the ion source and a substantial fraction of the ions in the transport tube are extracted.
Efficiency of an on-line isotope separator system employing cooled and NaCl-loaded He-jet methods
1976
Abstract A pure helium-jet at liquid nitrogen temperature coupled to a Nielsen type ion source, and a NaCl-loaded helium-jet coupled to a hollow-cathode ion source have been investigated as means to connect a cyclotron target chamber on-line to a mass separator. Technical details and performances of some critical parts of the system are described. Total separation efficiencies measured under various experimental conditions for several nuclides vary between 0.01 and 1.0%.
Modelling nanoparticles formation in the plasma plume induced by nanosecond pulsed lasers
2012
International audience; Nanoparticles formation in a laser-induced plasma plume in the ambient air has been investigated by using numerical simulations and physical models. For high irradiances, or for ultrashort laser pulses, nanoparticles are formed by condensation, as fine powders, in the expanding plasma for very high pairs of temperature and pressure. At lower irradiances, or nanosecond laser pulses, another thermodynamic paths are possible, which cross the liquid-gas transition curve while laser is still heating the target and the induced plasma. In this work, we explore the growth of nanoparticles in the plasma plume induced by nanosecond pulsed lasers as a function of the laser irra…
Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion.
2015
An open-ring ion trap, also referred to as transparent trap was initially built up to perform $\beta$-$\nu$ correlation experiments with radioactive ions. This trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single $^{40}$Ca$^+$ ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on $^{40}$Ca$^+$ ions, starting from large clouds and reaching single ion sensitivity.…