The authors describe a method for the measurement of secondary electron emission coefficients and demonstrate the use of this approach for the measurement of secondary electron yields for titanium, copper, and carbon ions incident upon an aluminum target. The method is time-resolved in that a series of measurements can be obtained within a single ion beam pulse of several hundred microseconds duration. The metal ion beams were produced with a vacuum arc ion source, and the ratio of secondary electron current to incident ion current was determined using a Faraday cup with fast control of the electron suppressor voltage. The method is relatively simple and readily applied and is suitable for measurements over a wide parameter range. The secondary yields obtained in the present work are of relevance to the measurement of ion current and implantation dose in plasma immersion ion implantation.

Optical emission spectra from plasma produced by a copper vacuum arc with argon and nitrogen have been investigated for the case when the plasma was guided by a straight solenoid. The spectra have been compared with those obtained from inductively coupled rf multicusp discharge in the 10−4–10−2 Torr argon and nitrogen pressure range and at an input power of up to 500 W. It has been found that the spectral line intensity distributions of neutral and ion species for arc and rf discharge were different. Also, the intensity evolutions of the lines have shown a different behavior between the arc current and rf power. Electron excitation temperature (Tex) for rf argon plasma at low pressure has been found to be approximately 2.5 eV which was about ten times higher than for Cu-argon arc discharge. Possible mechanisms of ionization-excitation of guest atoms/molecules in the case of metal vacuum arc discharge are discussed.

Optical emission spectroscopy in the range 200-800 nm was applied for investigation of the copper plasma produced by a metal vapour vacuum arc plasma source. The experiments were conducted for the cases when the plasma was guided by straight and Ω-shaped curved solenoids as well as without solenoids, and also for different vacuum conditions. It was found that, besides singly- and doubly-charged ions, a relatively high concentration of excited neutral copper atoms was present in the plasma. The relative fraction of excited atoms was much higher in the region close to the cathode surface than in the plasma column inside the solenoid. The concentration of excited neutral, singly- and doubly-ionized atoms increased proportionally when the arc current was increased to 400 A. Some weak lines were attributed to more highly ionized copper species and impurities in the cathode material.

Burning voltages of vacuum arcs were measured for 54 cathode materials and compared with literature data. As anticipated, a correlation between the arc burning voltage and the plasma temperature was found. However, more importantly, a correlation between the cohesive energy of the cathode material and the arc burning voltage could be demonstrated. This link between a cathode material property, the cohesive energy, and a discharge property, the arc burning voltage, is essential for the operation of the vacuum arc discharge because is determines the plasma temperature. Energy balance considerations show that this “cohesive energy rule” is responsible for several other secondary relationships, such as the correlation between the mean ion charge state and the boiling temperature of the cathode.

A 150-kV, high-current, non-mass-analyzed ion implanter based on a modified duoplasmatron ion source and a completely computerized control has been developed for industrially applicable ion beam surface engineering at Chiang Mai University. High-current (∼mA) N-ion implantation in steels and alloys and other ion beam techniques such as single-ion-beam assisted deposition have been explored using the facility for modification of tribological properties. The ion implanter has been engaged in industrial service to local customers in implanting various practical objects. The ion implantation for both academic and applied purposes has proved to be successful in improving hardness and wear resistance as well as prolonging lifetime of the ion-beam-processed tools.

We have developed a new technique for stable production of lanthanide negative ions in a cesium sputter ion source without damage to the ionizer. Lanthanide elements sticking to a cesium ionizer deteriorate an ionization efficiency of the ionizer because of their characteristics such as low vapor pressures and low work functions. We have resolved the problem to make a sputter cathode that has a predrilled double layer structure. Cerium oxide powder pressed in the cathode pellet was covered by tungsten and drilled. Using this cathode, we achieved smaller solid angle emission of the sputtered lanthanide elements from the bottom of the drilled hole, and most of them could pass through the center hole of the ionizer. As a result, damage to the ionizer decreased, and stable operation of the ion source was successfully achieved with a cerium oxide beam current of 600 nA for 24 h continuous operation. The technique was applied for production of other rare earth ions.

A metal vapor vacuum are (MEVVA) ion source has been constructed and installed at Chiang Mai University. The cathode-insulator-trigger electrode system and the cooling efficiency were found to be reliable during the source operation (without the cathode-insulator replacement), with total number of pulses of approximately 3 X 10(5) and with the repetition rate of up to 5.5 pps at 200 A are current. The main are and plasma ion current-voltage characteristics have been measured. The maximum plasma ion saturation current obtained at 3 cm distance from the cathode was approximately 6 A and the coefficient of transformation of the are current to the ion current was found to approach 3%. Preliminary experiments with copper film deposition on some dielectric substrates are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.

High and low Cr-content tool steels, SKD11 and SKS3, are implanted successively with 50 keV Cr-ions and 90 keV N2-ions to fluences of 4×1017 Cr+ cm−2 and 4×17 N+ cm−2. Microhardness and wear tests, in either dry air or diluted NaCl+H2SO4 solution environments, are used to investigate the effects of the multiply ion-implanted steel surface modification; these results are compared with singly Cr- and N-ion-implanted surfaces. The role of Cr-ion implantation in improving hardness and wear resistance of the steels in a dry-air environment is inferior to that of N-ion implantation, even affecting the co-implantation effectiveness on increasing hardness and wear resistance. However, combined Cr- and N-ion implantation can more positively enhance wear resistance in the salt–acid solution environment for the low-Cr steel than the high-Cr steel. XRD analysis supplies evidence for an explanation of the results.

An ion beam center has been established at Chiang Mai University in Thailand with the recently completed construction of a self-developed, 150 kV, two-beam-line (non-analyzed and analyzed) ion implantation facility and a 20 kV, 3 mA, non-analyzed ion implanter based on a duoplasmatron ion source. Using these facilities, a program of heavy ion implantation in metals and alloys is being carried out. The present work is focused on various nitrogen ion implantations of steels for local industry. This paper reports our research results including data on the hardness and wear resistance of local stainless steels, carbon steels and mild steels as a function of ion doses, and data on the oxidation behavior and tribological properties of ion implanted steels. Also discussed are high current, high dose and low energy ion implantation, and implantation in practical objects. Experimental data on implantations beneficial to the mechanical and chemical properties of the steels are presented and provide baselines for industrial applications.