Cold Cathode Electron Beam Research Articles

Generation of hardened steel surfaces with adjustable roughness by means of a pulsed electron beam

In this work we are utilizing a Pulsed Cold Cathode Electron Beam (PCCEB) for steel surface treatment that presents distinct properties as compared to other beam sources for rapid heating of metal surfaces. The possibility of producing different surface transformations like, melting and solid–solid transformations by adjusting the gun control parameters is demonstrated. It is shown that for the same base material, different pulse conditions give rise to distinct structures, a roughened or smooth martensitic surface or a smooth pearlite layer several microns thick. For the liquid–solid transformation, it is shown for the first time that with an adequate impurity content the instability onset threshold (giving rise to a rough topography) is different from the melting threshold. Hence, by controlling the discharge parameters, it is possible to obtain different topographies with similar crystallographic structure and hardness, allowing an adjustment of the final roughness to the particular application requirements.

Stabilization of a cold cathode electron beam glow discharge for surface treatment

We have demonstrated that the reproducibility of electron beam pulses generated by a high power, cold cathode glow discharge is greatly improved by adding a small continuous keep-alive discharge current. A current of the order of 200 μA was found to limit the shot to shot current variation to within 1.5%. This stabilization in turn reduces by an order of magnitude the fluctuations of the energy density deposited on the target, demonstrating a reliable energy source for surface treatment.

Electrical transport and related properties of zone-melt-recrystallized silicon-on-insulator films

Electrical transport properties of zone-melt-recrystallized Si films of Si-on-Insulator wafers were investigated using resistivity and Hall effect measurements between 77 and 300 K. Both graphite strip and cold cathode electron beam methods were used for zone melting which produced high resistivity (≳103 Ω cm at room temperature) recrystallized films. Phosphorus implantation into the silicon films to a dopant level of 1×1016 cm−3 and subsequent annealing at 1100 °C reduced the room-temperature resistivities to ∼1 Ω cm. Hall mobilities of 950 cm2/V s were observed at room temperature for both materials after the implant anneal sequence. However, for temperatures less than 150 K, the mobility is higher in graphite strip than in electron beam recrystallized films. This behavior is consistent with the relative crystalline qualities of the two films as determined by electron channeling and x-ray diffraction. It is noteworthy that a deep level was observed at 0.2 eV below the conduction band in the graphite strip recrystallized film but not in the electron beam recrystallized samples.

Cold Cathode Electron Beam Recrystallization of Soi Films

AbstractA cold cathode line source electron beam system for forming SOI films by zone melt recrystallization is described. Possible advantages gained from using a cold cathode electron beam include the controllability of the beam profile and power level, as well as straight-forward scaling to recrystallization of 6 or 8 inch wafers. A computer-based melt width control procedure incorporating feedback to the line intensity from optical observation of the molten zone is also described. This technique allows direct control and adjustment of the melt zone over widths typically from 1 to 3 mm.

Cold-cathode, glow-discharge, electron-beam gun pumped short pulse CO 2 lasers

A pulsed cold-cathode glow-discharge electron beam gun emitting an electron-beam of 150 keV energy and 45 cm 2 cross-sectional area has been used to pump a short pulse CO 2 laser. A fast discharge capacitor bank was used to help make the design simpler than that employed in liquid coaxial lines. The system developed is capable of producing a CO 2 laser pulse of 1 J for about 200 ns duration.

Low energy x-ray preionization source for discharge excited lasers

A low voltage (50 kV), low energy (3 J) x-ray preionization source has been developed specifically for avalanche discharge laser preionization. The new device uses a single stage high-voltage capacitor switched by a gradient grid hydrogen thyratron that drives a cold-cathode electron beam. Intense x-ray emission is produced by allowing the e beam to impact a high Z target foil. The entire system can operate up to 35 Hz repetition rate and produce an electron preionization density of ∼108 cm−3 in most rare-gas/halide laser gas mixtures.

The role of radiative transfer in pulsed laser plasma-target interactions

The plasma generated when a 2024 aluminum target was irradiated with the beam from a cold cathode electron beam laser (CCEBL) has been investigated with spectroscopic techniques. The target was designed to form the end plate of a differentially pumped slit assembly attached to a McPherson Model 225 visible-u.v.-v.u.v. monochromator. A pinhole in the center of the plate permitted plasma radiation to enter the monochromator from the back side of the target. Calibration with tungsten, deuterium and argon standards permitted quantitative plasma radiance measurements to be made in the region 115–600 nm using a range of diffraction gratings and photomultiplier tubes. The total radiant fluence observed (1 J/cm 2) was in reasonable agreement with the 1-1.2J/cm 2 of absorbed thermal fluence determined by independent thermal coupling measurements. Photographic spectra of the plasma (100–620 nm) were recorded and many features identified.

Nonchemical HF pulse laser pumped by e−beam−sustained discharge

Experiments with a pulsed discharge−pumped (nonchemical) HF laser are described. The laser discharge is sustained with a cold cathode electron beam gun. An output power of 8 kW/cm2 in a 2.5−μsec pulse length is obtained. Several observations regarding the laser mechanism are made.

Results of the time-dependent gain with a high-current electron-beam sustained discharge in CO2

A large-aperture cold-cathode electron beam with 150 kV and 0.4 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> has been used to sustain 1-μs discharges in a CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -laser mixture of 3/(1/2)/1. The electron density produced in the gas was approximately <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3.9 \times 10^{13}</tex> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> and thus for 1 atm a discharge power density of 150 J/1μs was achieved at 5.4 kV/cm for the sustainer electric field. The time-dependent gain for the 001-100 transition has been measured. Taking the experimental values of the discharge power, the gain has also been calculated using a kinetics program and a solution of the Boltzmann equation for the fractional power transfer. The good agreement between the experimental and calculated results gives confidence that the performance of cold-cathode electron-beam sustained-discharge CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> lasers can be predicted.