Search results for "Electric arc"
showing 8 items of 28 documents
Enhancing the extraction of laser-ionized beams from an arc discharge ion source volume
2018
© 2018 The Author(s) The Versatile Arc Discharge and Laser Ion Source (VADLIS) is a recently established ion source for the CERN-ISOLDE radioactive ion beam facility. It offers either electron-impact ionization (VADIS-mode) or resonance laser ionization (RILIS-mode). The choice of operating mode depends on the element of interest or the required beam purity. Particle-in-cell simulations using the VSim software show that the ion extraction efficiency of the VADLIS in RILIS-mode can be improved if it is equipped with an insulated extractor plate, to which an optimal voltage can be applied. This enables optimization of the RILIS-mode ion extraction independently of the electron density. Experi…
Vacuum electrical breakdown conditioning study in a parallel plate electrode pulsed dc system
2019
Conditioning of a metal structure in a high-voltage system is the progressive development of resistance to vacuum arcing over the operational life of the system. This is, for instance, seen during the initial operation of radio frequency (rf) cavities in particle accelerators. It is a relevant topic for any technology where breakdown limits performance and where conditioning continues for a significant duration of system run time. Projected future linear accelerators require structures with accelerating gradients of up to 100 MV/m. Currently, this performance level is achievable only after a multimonth conditioning period. In this work, a pulsed dc system applying voltage pulses over paral…
Blurring the boundaries between ion sources: The application of the RILIS inside a FEBIAD type ion source at ISOLDE
2016
For the first time, the laser resonance photo-ionization technique has been applied inside a FEBIAD-type ion source at an ISOL facility. This was achieved by combining the ISOLDE RILIS with the ISOLDE variant of the FEBIAD ion source (the VADIS) in a series of off-line and on-line tests at CERN. The immediate appli- cations of these developments include the coupling of the RILIS with molten targets at ISOLDE and the introduction of two new modes of FEBIAD operation: an element selective RILIS mode and a RILIS + VADIS mode for increased efficiency compared to VADIS mode operation alone. This functionality has been demonstrated off-line for gallium and barium and on-line for mercury and cadmi…
Simulation of forces and 3-D field arising during power autotransformer fault due to electric arc in HV winding
2002
Forces and three-dimensional magnetic fields in high-voltage winding due to an internal short circuit in a power autotransformer are calculated with the computer package OPERA 3D. The considered damage was caused by an electric arc. The materialized deformation of the winding part confirms the simulation results.
A hot cavity laser ion source at IGISOL
2008
A development program is underway at the IGISOL (Ion Guide Isotope Separator On-Line) facility, University of Jyvaskyla, to efficiently and selectively produce low-energy radioactive ion beams of silver isotopes and isomers, with a particular interest in N=Z 94Ag. A hot cavity ion source has been installed, based on the FEBIAD (Forced Electron Beam Induced Arc Discharge) technique, combined with a titanium:sapphire laser system for selective laser ionization. The silver recoils produced via the heavy-ion fusion-evaporation reaction, 40Ca(58Ni, p3n)94Ag, are stopped in a graphite catcher, diffused, extracted and subsequently ionized using a three-step laser ionization scheme. The performance…
Experimental investigation of the relation between H− negative ion density and Lyman-α emission intensity in a microwave discharge
2016
International audience; A new mechanism for producing negative ions in low density and low power hydrogen plasmas was proposed recently. It refers to anion formation due to collisions between hydrogen atoms being in the first excited state. The proposed mechanism was indirectly supported by the quadratic relation observed between the extracted negative ion current and Lyman-α radiation of a filament-driven arc discharge, when borrowed data from the literature were combined. The present work provides experimental data comparing directly the absolute negative ion density and Lyman-α radiation in an ECR-driven hydrogen plasma source. The previously mentioned quadratic relation is not observed …
A comparative study of the behaviour of silver, copper and nickel submitted to a constant high power flux density
2005
In this paper, we present a numerical simulation of three metal cathode (silver, copper and nickel) submitted to a constant flux power flux density ranging between and . The goal is to compare the interface evolution (vaporization and liquefaction rate, appearance time of liquid and vapour, energetic repartition) to predict the behaviour of the cathodes during an electric arc.
Photoelectron emission experiments with ECR-driven multi-dipolar negative ion plasma source
2017
Photoelectron emission measurements have been performed using a 2.45 GHz ECR-driven multi-dipolar plasma source in a low pressure hydrogen discharge. Photoelectron currents induced by light emitted from ECR zone and H− production region are measured from Al, Cu, Mo, Ta, and stainless steel (SAE 304) surfaces as a function of microwave power and neutral hydrogen pressure. The total photoelectron current from the plasma chamber wall is estimated to reach values up to 1 A for 900 W of injected microwave power. It is concluded that the volumetric photon emission rate in wavelength range relevant for photoelectron emission is a few times higher in arc discharge. peerReviewed