[en] The discharge mechanism of this source is based on the use of mixed discharge formed by the use of both RF-driven (15 MHz-300W) and vacuum arc to create discharge plasma of higher intensity. The basic construction of the source is in the form of a cylindrical anode which is immersed in non homogeneous axial magnetic field of 500Gauss measured at the source center. The anode is terminated from its both ends with two cathodes, thus allowing the electrons to be oscillate between the two cathodes. An internal antenna is used to couple the RF power to the plasma through a matching circuit formed from an inductor connected in parallel with capacitor, in order to insure maximum power transfer to the plasma. The oscillating electrons thus absorb energy from both RF and DC fields in the gaps between the cathodes and the anode due to the arc discharge. In order to investigate and optimize the source characteristics, the influence of the discharge pressure, magnetic field, discharge voltage and RF power on the source characteristics have been studied. The source is considered self extracted ion current and could deliver ion currents of ∼10A for thin beam (diameter ∼4mm.) and ∼20 mA for broad beam (diameter ∼6cm.) at ∼200V extraction voltage. The plasma is diagnosed using double Langumier probes. The plasma intensity could reach ∼8x10¹¹ elec./cm³ and the plasma temperature ∼14 eV. Lower ignition voltage (50 up to 200V) and higher plasma intensity feature the characteristics of this source. The beam diagnostics (for thin beam) of this source are measured, which include: the beam profiles, beam emittance, energy spread and distribution of the ion species in the ion beam. The increase of the anode voltage affects decrease of the beam emittance, while the energy spread increases with the decrease of the discharge pressure. The beam emittance is found to be around 200 up to 400 mm.m.rad. and the energy spread of the ions in the ion beam is around 40 up to 80 eV. The source could deliver Argon ion species up to Ar⁺⁵. The beam profiles show that the beam is more convergent with the increase of the accelerating voltage and with the use of proper capacitors between the extraction electrodes

No abstract available

[en] Plasma supply to the extraction region, which is of essential importance in high-current ion sources, is investigated experimentally and theoretically. The theory uses the model that the mechanism of plasma supply is a one-dimensional plasma diffusion, and indicates that the mean free path of ions lambda sub(i) and the electron temperature T sub(e) should be large for the effective supply; as an example, lambda sub(i)√T sub(e) >= 7 cm.eV sup(1/2). The experiments show qualitiative agreement with the theory with regard to the effect of the mean free path of ions on the plasma supply, and indicate that a decrease in plasma density is brought about by beam extraction when the supply is insufficient. The diffusion model used is a simple one, but is thought to be useful for the understanding of ion source performance. (author)

[en] Measurements of the normalized emittance of the beam produced by the Advanced Test Accelerator (ATA) injector yielded values near 0.4 Radian-Centimeters at currents up to 10 kAmps. The instrument was also used to obtain beam-current-density profiles in two dimensions at the entrance mask of the instrument

[en] Design of a simple ion source with long service life is described. Gaseous discharge in plasma generator burns between anode with outlet and heated cathode, made of tungsten wire, 1.5 mm in diameter. Additional electrode, being at floating potential is used to reduce thermionic cathode destruction in result of cathode sputtering. This electrode, decreasing sufficiently plasma density near thermionic cathode without change of its emission current, reduces ion flux from plasma on thermionic cathode. This results to sharp decrease of its destruction rate under ion bombardment service life tests of the ion source were conducted for argon during 100 h. Any noticeable destructions of structural components, including thermionic cathode, were not revealed after tests

[en] A description and results of tests of device for automatic extraction of ions from a high-frequency ion source are presented. The automatic regime is realized by introducing feedback with respect to the current of the source cathode and requires low sinusoidal modulation of the exctracting voltage. By varying the power of the discharge the beam current was controlled in the 90-1470μA range with automatic preservation of the optimal conditions in the extraction system. The device was used on a 210-kV neutron generator

[en] Vacuum arc ion sources provide a convenient tool for the production of intense beams of metal ions. The sources are relatively easy to construct and they can produce beams from all of the solid metals as well as from compounds, alloys, and mixtures. We have made a number of different kinds of such sources over the course of our development work at LBL in the past decade, from very small open-quote open-quote thumb-size close-quote close-quote versions to a very large one with a 50 cm diameter extractor. Beam current ranges from a few milliamperes up to almost 10 A and extraction voltage from about 1 to 100 kV. Multicathode versions have been made so that one can switch between metal ion species simply and quickly. Most of the sources have been operated in a repetitively pulsed mode, and we close-quote ve also tested a dc version. Here we outline some construction features of the array of vacuum arc ion sources that we close-quote ve developed and used, and describe their performance and limitations. copyright 1996 American Institute of Physics

[en] An ion beam source is described which is adapted to provide a plurality of planar ion beams. The centres of the beams are superimposed and their planes are at an angle to the line joining their centres such that the projection of the beams in a direction orthogonal to that joining their centres is continuous. The ion beams are produced by superposed slits in extraction electrodes. The length L, pitch P and angle THETA of the slits are such as to ensure uniform coverage of a target passed through the beams. (author)

[en] The subject of the paper is theoretical and experimental studies of development of the filament instability of a high-current ion beam and its stabilization by an external longitudinal magnetic field. The experiments were carried out at an installation being the functional model of the ion induction accelerator injector. Since the instability increment at beam current density of ≥ 10³ A/cm² is equal to 10⁸ s^-1 and beam flight time is ∼ 5x10^-8 s, the beam splits into current-carrying filaments that is observed in the experiment

[en] In designing an accelerator for high currents it is evident that beam losses in the machine must be minimized, which implies well matched beams, and that adequate acceptance under severe space charge conditions must be met. This paper investigates the input parameters to an Alvarez type drift-tube accelerator resulting from such factors