James E. Galvin

Miniature high current metal ion source

A small, simple ion source for the production of high brightness beams of metal ions is described. A metal vapor vacuum arc discharge is used to establish the high density plasma from which the ion beam is extracted. The source is finger sized, and can produce pulsed metal ion beams with current up to the 10‐mA range.

Broad-beam multi-ampere metal ion source

An embodiment of the MEVVA (metal vapor vacuum arc) high current metal ion source has been developed in which the beam is formed from a 10‐cm‐diam set of extractor grids and which produces a peak beam current of up to several amperes. The source, MEVVA V, operates in a pulsed mode with a pulsewidth, at present, of 0.25 ms and a repetition rate of up to several tens of pulses per second (power supply limited). The multi‐cathode feature that was developed for the prior source version, MEVVA IV, has been incorporated here also; one can switch among any of 18 separate cathodes and thus metallic beam species. Maximum beam extraction voltage is over 90 kV, and since the ion charge states are typically from Q=1 to 5, depending on the metal employed, the ion energy in the extracted beam can thus be up to several hundred keV. This source is a new addition to the MEVVA family of metal ion sources, and we are at present investigating the operational regimes and the limits to the source performance. In this article w...

Some novel design features of the LBL metal vapor vacuum arc ion sources

The family of MEVVA (metal vapor vacuum arc) high current metal ion sources developed at LBL over the past several years has grown to include a number of different source versions with a wide range of some of the design and operational parameters. The MicroMEVVA source is a particularly compact version, about 2 cm diam and 10 cm long, while the MEVVA IV weighs some 30 kG. MEVVAs IV and V incorporate multiple cathode assemblies (16 and 18 separate cathodes, respectively), and the operating cathode can be switched rapidly and without downtime. The new MEVVA V embodiment is quite compact considering its broad beam (10 cm), high voltage (100 kV), and multiple cathode features. The large‐area extractor grids used in MEVVA V were fabricated using a particularly simple technique, and they are clamped into position and can thus be changed simply and quickly. The electrical system used to drive the arc is particularly simple and incorporates several attractive features. In this article we review and describe a number of the mechanical and electrical design features that have been developed for these sources.

Simple, safe, and economical microwave plasma‐assisted chemical vapor deposition facility

A simple and economical microwave plasma‐assisted chemical vapor deposition facility has been developed and used for synthesis of diamond thin films. The system is similar to those developed by others but includes several unique features that make it particularly economical and safe, yet capable of producing high quality diamond films. A 2.45‐GHz magnetron from a commercial microwave oven is used as the microwave power source. A conventional mixture of 0.2% methane in hydrogen is ionized in a bell jar reaction chamber located within a simple microwave cavity. By using a small hydrogen reservoir adjacent to the gas supply, an empty hydrogen tank can be replaced without interrupting film synthesis or causing any drift in plasma characteristics. Hence films can be deposited continuously for arbitrarily long periods while storing only a 24‐h supply of explosive gases. System interlocks provide safe start‐up and shut‐down and allow unsupervised operation. Here we describe the electrical, microwave, and mechani...

Charge state distribution studies of the metal vapor vacuum arc ion source

We have studied the charge state distribution of the ion beam produced by the MEVVA (metal vapor vacuum arc) high current metal ion source. Beams produced from a wide range of cathode materials have been examined and the charge state distributions have been measured as a function of many operational parameters. In this article we review the charge state data we have accumulated, with particular emphasis on the time history of the distribution throughout the arc current pulse duration. We find that, in general, the spectra remain quite constant throughout most of the beam pulse, as long as the arc current is constant. There is an interesting early‐time transient behavior when the arc is first initiated and the arc current is still rising, during which time the ion charge states produced are observed to be significantly higher than during the steady current region that follows.

Some novel surface modification applications of a new kind of high current metal ion implantation facility

A novel high current metal ion implantation facility has been developed in which a metal vapor vacuum arc ion source is used. The source is operated in a pulsed mode, with pulse width 0.25 msec and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV and beam current up to several amperes peak and 10–20 mA time averaged delivered onto target. Implantation is done in a broad beam mode with a direct line of sight from ion source to target. Virtually all of the solid metals of the Periodic Table can be used. The facility has been used for a variety of different research applications, including metallurgical surface modification, high temperature oxidation resistance, ‘fine tuning’ of the composition of highTc superconducting thin films, formation of buried conducting layers in silicon, and other research purposes. Here we describe the implantation facility and some of the research programs carried out at our laboratory and collaboratively with others.

Multiply charged metal ion beams

Abstract The metal vapor vacuum arc is a prolific generator of highly ionized metal plasma in which the ions are in general multiply stripped. We have utilized this plasma production mechanism to make a high current metal ion source. The metal vapor vacuum arc ion source is thus a laboratory tool for providing high quality, high current beams of a wide range of metal ion species. Charge state spectra have been measured using a time-of-flight diagnostic. In this paper we review the ion source development program, describe the various embodiments of the concept that have been made, and summarize those experimental results relating to the ion charge states that can be produced.

Versatile high current metal ion implantation facility

Abstract A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multicathode, broad-beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred kiloelectronvolts because of the ion charge state multiplicity, and with a beam current of up to several amps peak pulsed and several tens of milliamps time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line of sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it.

A broad-beam, high-current metal-ion implantation facility

Abstract We have developed a high-current metal-ion implantation facility with which high-current beams of virtually all the solid metals of the periodic table can be produced. The facility makes use of a metal-vapor vacuum-arc ion source which is operated in a pulsed mode, with 0.25 ms pulse width and a repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge-state multiplicity; beam current is up to several amperes peak and around 10 mA time-averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the “seeding” of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III–V compounds.

Development of a dc, broad beam, Mevva ion source

We are developing an embodiment of metal vapor vacuum arc (Mevva) ion source which will operate dc and have a very large area beam. In preliminary testing, a dc titanium ion beam was formed with a current of approximately 0.6 A at an extraction voltage of 9 kV (about 18 keV ion energy, by virtue of the ion‐charge state distribution) using an 18‐cm‐diameter set of multiaperture extraction grids. Separately, we have tested and formed a beam from a 50‐cm‐diameter (2000 cm2) set of grids using a pulsed plasma gun. This configuration appears to be very efficient in terms of plasma utilization, and we have formed beams with a diameter of 33 cm (FWHM) and ion current up to 7 A at an extraction voltage of 50 kV (about 100 keV mean ion energy) and up to 20 A peak at the current overshoot part of the beam pulse. Here we describe this part of our Mevva development program and summarize the results obtained to date.