419 research outputs found
Role of the plasma-electrode bias and the transverse magnetic field upon H- ion extraction in the negative ion source
Non peer reviewedPublisher PD
Study of the plasma near the plasma electrode by probes and photodetachment in ECR-driven negative ion source
Contributions to the conference will be published, following peer review, in the American Institute of Physics conference proceedings.International audienceThe effect of the plasma electrode bias on the plasma characteristics near the extraction aperture in a large volume hybrid multicusp negative ion source, driven by 2.45 GHz microwaves, is reported. Spatially resolved negative ion and electron density measurements were performed under various pressures (1-4 mTorr) by means of electrostatic probe and photodetachment technique
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Increasing the Space Charge Limit and Other Effects of Cesium Seeding in Hydrogen Negative Ion Sources
The role of cesium seeding in increasing the negative ion current in volume sources is described. By a reduction in the local plasma potential the current of extracted electrons is vastly reduced. As a result, cesium increases the fraction of the transverse space charge limit available to the ions by as much as a factor of three. In addition, cesium can increase the total space charge limit by injection of Cs+ into the presheath-a newly recognized phenomenon consistent with experimental measurements and determined from application of a Double-Vlasov model for negative ion extraction
TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz
The research reactor TRIGA Mainz is an ideal facility to provide neutron-rich
nuclides with production rates sufficiently large for mass spectrometric and
laser spectroscopic studies. Within the TRIGA-SPEC project, a Penning trap as
well as a beam line for collinear laser spectroscopy are being installed.
Several new developments will ensure high sensitivity of the trap setup
enabling mass measurements even on a single ion. Besides neutron-rich fission
products produced in the reactor, also heavy nuclides such as 235-U or 252-Cf
can be investigated for the first time with an off-line ion source. The data
provided by the mass measurements will be of interest for astrophysical
calculations on the rapid neutron-capture process as well as for tests of mass
models in the heavy-mass region. The laser spectroscopic measurements will
yield model-independent information on nuclear ground-state properties such as
nuclear moments and charge radii of neutron-rich nuclei of refractory elements
far from stability. This publication describes the experimental setup as well
as its present status.Comment: 20 pages, 17 figure
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High‐current D −
A beam of D{sup -} ions has been produced at 7-13 keV, with currents up to 2.2 {angstrom}, using charge exchange in sodium vapor. The beam profile is bi-Gaussian with angular divergence 0.7{sup o} x 2.8{sup o} and peak current density 15 mA/cm{sup 2}. The characteristics of the beam are in excellent agreement with predictions based on atomic cross sections. The sodium vapor target is formed by a jet directed across the beam. The sodium density drops rapidly in the beamline downstream from the charge exchange region, decreasing three orders of magnitude in 15 cm. Measurement and analysis of the plasma accompanying the beam demonstrate that plasma densities nearly equal to the beam density are obtained 1 m from the charge exchange medium. The plasma produced in the sodium is thus well confined to the charge exchange region and does not propagate along the beam
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