V. I. Gushenets

Simple and inexpensive time-of-flight charge-to-mass analyzer for ion beam source characterization

We describe the design, electronics, and test results of a simple and low-cost time-of-flight ion charge-to-mass analyzer that is suitable for ion source characterization. The method selects a short-time sample of the beam whose charge-to-mass composition is then separated according to ion velocity and detected by a remote Faraday cup. The analyzer is a detachable device that has been used for rapid analysis of charge-to-mass composition of ion beams accelerated by voltages of up to about 100kV.We describe the design, electronics, and test results of a simple and low-cost time-of-flight ion charge-to-mass analyzer that is suitable for ion source characterization. The method selects a short-time sample of the beam whose charge-to-mass composition is then separated according to ion velocity and detected by a remote Faraday cup. The analyzer is a detachable device that has been used for rapid analysis of charge-to-mass composition of ion beams accelerated by voltages of up to about 100kV.

Study of directed ion velocities in a vacuum arc by an emission method

Directed ion velocities in a vacuum arc discharge plasma are measured on the basis of a study of the ion emission current response to a rapid change of arc current. It is shown that these velocities are about 106 cm/s, are determined by the cathode material, and are almost independent of the ion charge number. Applying a magnetic field results in an increase in the directed ion velocity. As the gas pressure increases, the directed ion velocity decreases; this is the only case where the directed velocities are observed to depend on the ion charge number.

Electron-beam enhancement of ion charge state fractions in the metal-vapor vacuum-arc ion source

We report demonstrations of ion charge-state enhancement for an electron-beam metal-vapor vacuum-arc (E-MEVVA) ion source. Results with a lead cathode yielded a maximum ion charge state of Pb7+, which implies an ionization potential of at least 130 eV. Electron current densities j=70 A/cm2 and ionization times τ≅100 μs produced jτ=9.2×10−3 C/cm2 (5.8×1016 electrons/cm2). Standard analysis for these conditions indicates—somewhat surprisingly—that successive single (stepwise) ionization accounts for the present observations, even though the charge states are substantially higher than most previous results with MEVVA-based ion sources.

Electron-beam enhancement of the metal vapor vacuum arc ion source

We report detailed investigations of the electron-beam metal vapor vacuum arc (E-MEVVA) ion source. The experiments were performed in Moscow and Tomsk with nearly the same design of ion sources. We recently reported the first conclusive demonstration of electron-beam enhancement of MEVVA performance using lead and bismuth cathodes, which yielded maximum ion charge states of Pb7+ and Bi8+ for E-MEVVA, as compared to Pb2+ and Bi2+ for conventional MEVVA operation. In this article we report extensive results for additional cathode materials, further details of the Moscow and Tomsk ion sources, and a discussion of electron beam effects on E-MEVVA performance. These results can be considered as a proof of the E-MEVVA principle.

Current status of plasma emission electronics. I: Basic physical processes

This paper reviews the physical phenomena that accompany the emission of electrons and ions from plasma. The development of plasma emission electronics as an independent research field is closely associated with the name of its founder, Professor Kreindel Yu. E. The well-known advantages of plasma electron emitters (plasma cathodes) are the higher emission current density, the pulsed emission capability, and the wider range of residual gas pressures. A peculiar property of the plasma cathode is the possibility of extracting practically all electrons from plasma. The parameters of an ion and electron beam extracted from plasma carry information about the physical processes occurring in the plasma. This makes it possible to invoke emission methods to study the fundamental phenomena that take place in plasma of vacuum arc and low-pressures gas discharges.

Electron beam generation in a diode with a gaseous plasma electron source I: Plasma source based on a hollow anode ignited by a multi-arc system

We report on the operation of an electron diode with a cathode based on a hollow plasma anode (HPA) design. Six arc sources placed inside the anode cavity were used to produce a preliminary plasma. The latter was used to produce a high-current (up to 4 kA) gaseous discharge without formation of plasma spots at the anode wall and output grid. The plasma parameters inside the HPA were measured for different N2 and Xe gas pressures and discharge current amplitudes. It was found that the HPA operation is characterized by a negative anode potential fall and that the plasma density and temperature inside the anode are ≈6×1012 cm−3 and ≈9 eV, respectively. The characteristics of an electron diode and the generated electron beam were studied under an accelerating voltage amplitude ⩽250 kV and 400 ns pulse duration for different parameters of the HPA. It was found that in the beginning of the accelerating pulse the diode operates in a plasma prefilled mode while later the diode current is determined by the emissio...

Current status of plasma emission electronics: II. Hardware

This paper is devoted to the engineering embodiment of the modern methods for producing charged ion and electron beams by extracting them from the plasma of a discharge. Electron beams use to execute electron-beam welding, annealing, and surface heating of materials and to realize plasmochemical reactions stimulated by fast electrons. Ion beams allow realization of technologies of ion implantation or ion-assisted deposition of coatings thereby opening new prospects for the creation of compounds and alloys by the method that makes it possible to obtain desired parameters and functional properties of the surface. A detailed description is given to the performance and design of devices producing beams of this type: the ion and electron sources being developed at the laboratory of plasma sources of the Institute of High-Current Electronics of the Russian Academy of Sciences and the laboratory of plasma electronics of Tomsk State University of Control Systems and Radioelectronics.

Boron ion source based on planar magnetron discharge in self-sputtering mode.

An ion source based on a planar magnetron sputtering device with thermally isolated target has been designed and demonstrated. For a boron sputtering target, high target temperature is required because boron has low electrical conductivity at room temperature, increasing with temperature. The target is well-insulated thermally and can be heated by an initial low-current, high-voltage discharge mode. A discharge power of 16 W was adequate to attain the required surface temperature (400 degrees C), followed by transition of the discharge to a high-current, low-voltage mode for which the magnetron enters a self-sputtering operational mode. Beam analysis was performed with a time-of-flight system; the maximum boron ion fraction in the beam is greater than 99%, and the mean boron ion fraction, time-integrated over the whole pulse length, is about 95%. We have plans to make the ion source steady state and test with a bending magnet. This kind of boron ion source could be competitive to conventional boron ion sources that utilize compounds such as BF(3), and could be useful for semiconductor industry application.

Further development of the E-MEVVA ion source

We report detailed investigations of the electron-beam metal vapor vacuum-arc (E-MEVVA) ion source, which were performed jointly among the Institute for Theoretical and Experimental Physics, Moscow, Russia, the High Current Electronics Institute, Tomsk, Russia, and Brookhaven National Laboratory, USA. The experiments were performed in Moscow and Tomsk with nearly the same design of ion sources. Recently, the first successful ion charge states enhancement for this kind of ion source was demonstrated. This article presents comparisons of electron-beam effects and examines their influence on E-MEVVA performance. Substantial enhancement of high ion charge states enhancement was observed clearly in both experimental setups with two different methods of measuring the ion charge state distributions. These results can be considered as a proof of the E-MEVVA principle.

High-energy metal ion implantation for reduction of surface resistivity of alumina ceramic

In this work, the possibility to increase the surface conductivity of ceramic insulators through their treatment with accelerated metal ion beams produced by a MevvaV.Ru vacuum arc source is demonstrated. The increase in surface conductivity is made possible due to experimental conditions in which an insulated collector is charged by beam ions to a potential many times lower than the accelerating voltage, and hence, than the average beam ion energy. The observed effect of charge neutralization of the accelerated ion beam is presumably associated with electrons knocked out of the electrodes of the accelerating system of the source and of the walls of the vacuum chamber by the accelerated ions.