Rapid melting and quenching with microsecond current pulses

We report the use of microsecond current pulses to transform layered crystalline Ni---Zr films to amorphous alloys. The starting materials were electron-beam- or sputter-deposited multilayers with a composition modulation wavelength of 34 nm, an average composition of Ni63Zr37 and a total thickness of 680 nm. The electrical pulses were approximately rectangular and about 3 ms in duration, with an intensity of several hundred amperes, directly coupling 1.6-3 J of energy uniformly into the film. By monitoring current and voltage, the reaction and melting of the sample were observed, and the total energy of the pulse was easily computed. A sharp threshold in pulse energy for sample transformation was observed. A simple heat flow calculation demonstrated that the chemical energy released by the reaction and the change in diffusion kinetics as the sample temperature exceeded the glass transition temperature of the amorphous alloy are responsible for this sudden onset. The maximum temperature estimated from this calculation is below the melting point of the constituents, and the cooling rate is 107 - 108 K s-1 which is in agreement with the formation of amorphous alloys.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27478/1/0000521.pd

Ablation plasma ion implantation using a dc power supply

Experiments are reported in which ablation plasma ion implantation (APII) has been demonstrated using a dc power supply. The ability to use a dc power supply for APII has been accomplished by using a perpendicular orientation between the target and the substrate. This perpendicular orientation significantly reduces the arcing between the target and the substrate, in contrast to previous experiments using a parallel target–substrate orientation. With this new technique a KrF laser may be fired during the dc high voltage, accelerating full-energy ions. Initial experiments using dc APII have shown that Ti is deposited and implanted onto the Si substrate, with the highest concentration of Ti located beneath the surface of the film. The deposition/implantation of Ti ions onto Si was verified by X-ray photoelectron spectroscopy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47038/1/339_2004_Article_2585.pd

Heating at the electron cyclotron frequency in the ISX-B Tokamak

[[abstract]]Results are reported of electron-cyclotron-heating experiments in which 80 kW of microwave power from a 35-GHz gyrotron is injected into a Tokamak with large single-pass absorption. For 10-ms microwave pulses, incident from the high-field side of the torus, the central electron temperature increases from 850 to 1250 eV, in agreement with empirical transport-code calculations. For the first time it is demonstrated that electron temperature in a Tokamak scales linearly with electron-cyclotron-heating power[[fileno]]2010126010096[[department]]物理

Laser enhanced microwave plasma isotope separation. Final report, September 30, 1992--September 29, 1995

The experimental research was to focus on laser excitation of a low abundance isotope and then ionize and separate the isotope of low abundance using a microwave/ECR discharge at 2.45 GHz. A small compact electron cyclotron resonance ion source, which uses permanent magnets, was constructed during this project. The dye laser was purchased and later an excimer laser had to also be purchased because it turned out that the dye laser could not be pumped by our copper laser. It was intended that the dye laser be tuned to a wavelength of 670.8 nm, which would excite {sup 6}Li which would then be preferentially ionized by the ECR source and collected with a charged grid. The degree of enrichment was to be determined using thermal ionization mass spectrometry. The final objective of this project was to assess the feasibility of this system to large-scale production of stable isotopes. However the funding of this project was interrupted and we were not able to achieve all of our goals