Over the past decade, researchers in Japan, Russia, and the United States have been investigating the application of intense-pulsed-ion-beam (IPIB) technology (which has roots in inertial confinement fusion programs) to the surface treatment and coating of materials. The short range (0.1–10 μm) and high-energy density (1–50 J/cm2) of these short-pulsed (t ≥ 1 μs) beams (with ion currents I = 5–50 kA, and energies E = 100–1,000 keV) make them ideal flash-heat sources to rapidly vaporize or melt the near-surface layer of targets similar to the more familiar pulsed laser deposition (PLD) or laser surface treatment. The vaporized material can form coatings on substrates, and surface melting followed by rapid cooling (109 K/s) can form amorphous layers, dissolve precipitates, and form nonequilibrium microstructures.An advantage of this approach over laser processing is that these beams deliver 0.1–10 KJ per pulse to targets at expected overall electrical efficiencies (i.e., the ratio of extracted ion-beam energy to the total energy consumed in generating the beam) of 15–40% (compared to < 1% for the excimer lasers often used for similar applications). Consequently IPIB hardware can be compact and require relatively low capital investment. This opens the promise of environmentally conscious, low-cost, high-throughput manufacturing. Further, efficient beam transport to the target and excellent coupling of incident ion energy to targets are achieved, as opposed to lasers that may have limited coupling to reflective materials or produce reflecting plasmas at high incident fluence. The ion range is adjustable through selection of the ion species and kinetic energy, and the beam energy density can be tailored through control of the beam footprint at the target to melt (1–10 J/cm2) or to vaporize (10–50 J/cm2) the target surface. Beam pulse durations are short (≥ 1 μs) to minimize thermal conduction. Some disadvantages of IPIB processing over laser processing include the need to form and propagate the beams in vacuum, and the need for shielding of x-rays produced by relatively low-level electron current present in IPIB accelerators. Also these beams cannot be as tightly focused onto targets as lasers, making them unsuitable for applications requiring treatment on small spatial scales.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0883769400035739

Intense Ion-Beam Treatment of Materials

A 300 keV, 30 kA, 1 μs intense beam ofcarbon, oxygen, and hydrogen ions is used for the surface treatment of AISI-4620 steel coupons, a common material used in automotive gear applications. The beam is extracted from a magnetically-insulated vacuum diode and deposited into the top 1 μm of the target surface. The beam-solid interaction causes a rapid melt and resolidification with heating and cooling rates of up to 1010 K/s. Treated surfaces are smoothed over 1 μm-scale lengths, but are accompanied by 1 μm-diameter craters and larger-scale roughening over ≥ 10 μm, depending on beam fluence and number of pulses. Treated surfaces are up to 1.8 × harder with no discernible change in modulus over depths of 1 μm or more. Qualitative improvements in the wear morphology of treated surfaces are reported.

/pdf/surface-modification-of-aisi-4620-steel-with-intense-pulsed-ad7gpx96r3.pdf

Surface modification of AISI-4620 steel with intense pulsed ion beams

Two sources of high-power ion beams of nanosecond duration are described, a MUK and a TEMP unit They generated ions with energies of up to 150 and 300 keV, respectively, and the pulse duration was 20–200 and 50 ns, respectively. For the MUK unit, beam parameters for heavy ion implantation (Al n+ , Mg n+ , Fe n+ , W n+ , etc.) were as follows: current density ranging from 1 to 10 A cm −2 and total ion flux energy up to 20 J. For the TEMP unit, the following beam parameters were used for H + and C n+ ions: current density 40–200 A cm −2 and total ion flux energy 0.3–0.5 kJ. The sources are powered by various diode systems and can be applied in material science for scientific research and technology.

High-power ion beam sources for industrial application

The author presents a bibliography covering the field of electrical discharges in vacuum, comprising both electrical breakdown in vacuum and vacuum arcs. A brief section lists some review papers which would be helpful to the novice in this field. The bulk of the presentation consists of bibliographic listings arranged by year of publication and alphabetically by author within each year. An author index refers one to all papers authored or coauthored by a particular person. >

Electrical discharges in vacuum: 1980-90

Optical metallography, transmission electron microscopy, and phase analysis were used to study the mechanisms of structural transformations in the surface layer of thickness Δh≈0.2 μm for single crystals and polycrystals of metals and alloys irradiated with high-power ion beams (HPIB's). Characteristic features of the formation of the surface relief and variations in phase constitution and defect substructure of pure metals (Ni, Mo) and single-phase (Mo–Re, Ni3Al) and double-phase (V–ZrO2) alloys have been found in relation to the ion beam power density Q=(1–10)×107 W/cm2. Common features and distinctions in the formation of the microstructure of metallic materials belonging to different classes under HPIB irradiation have been revealed. Based on the predictions of a numerical simulation of the time-dependent temperature fields and the melting and evaporation processes in the surface layer, the mechanisms for the phase-structure modification of metal and alloy surfaces are analyzed.

Features of the morphology, defect substructure, and phase composition of metal and alloy surfaces upon high-power ion beam irradiation

Sources of high power ion beams for technological applications

Experimental results are presented concerning the acceleration of heavy ion beams generated in a planar diode and in a magnetically insulated strip diode by means of explosive emission. In case of carbon ions, by application of two voltage pulses (for plasma generation and ion acceleration, respectively) separated by an optimized pause, and by beam focusing current densities of 200 A/cm2, currents of 3 to 4 kA and beam divergences of less than 4± could be achieved.

S.A. Pechenkin

Papers

Sources of high power ion beams for technological applications

Generation of Heavy Ion Beams