Abstract:
In a first embodiment of an improved diamond deposition cell, a chamber is evacuated to a low pressure and a graphite element in the chamber is heated to a selected high temperature and heats a substrate positioned within the chamber spaced by a selected gap from the graphite body to a selected lower temperature. Hydrogen or a mixture of hydrogen and hydrocarbon gas is admitted to the chamber and part of the hydrogen reacts with the hot graphite body to form atomic hydrogen and hydrocarbon gasses. Hydrogen and hydrocarbon gasses cycle repeatedly across the gap between the facing surfaces of the body and the substrate in the kinetic regime resulting in a net transfer of carbon to the substrate and its deposition as diamond crystals or film on the substrate. In a second embodiment, the graphite body is heated by combusting gasses in a cavity therein. Products of such combustion, hydrogen and, optionally, additional hydrocarbon gas are admitted to the gap between the surfaces of the graphite body and the substrate. The temperatures of the facing surfaces, the pressure in the gap and the ratio of the constituent gasses results in carbon atoms being deposited on the substrate in the form of diamond film and other carbon products.
Abstract:
A heater/emitter for a rocket engine assembly utilizes a resistance heated wire coil or coils which may also function as a cathode emitter or as a thermal driver for an auxiliary emitter. This heater/emitter may if desired be formed into a bifilar and may be supported by the wire lead itself or by isolated supports. The power leads are located in a lead channel and feature an overwrapping of similar wire material which reduces the internal resistance heating of the lead to increase the electrical conductivity of the supporting lead and increase the thermal conduction thereof to establish a cooler and structurally-stronger lead. A plurality of radiation discs or shields are spaced along the leads to further minimize energy losses from the heater out of the lead channel. The heater/emitter itself is enclosed, except for the lead channel, by a heat exchanger housing. The function of this housing is to accept energy from the hot heater coil and in turn transfer that energy to a fluid flowing through the heat exchanger. Power is transferred from the hot heater coil to the heat exchanger firstly by means of radiation heat transfer, and secondly by impingement of thermionic electrons accelerated thru a potential imposed between the emitter and the heat exchanger. This packaging approach permits radiation transfer efficiencies, from coil to heat exchanger, of 90 to 95 percent. The thermionic electron emission and acceleration efficiency approaches 100 percent. The dual energy transfer mode permits single device operation over wider power ranges and thrust levels than would be permitted by single mode devices. The device may be operated in the single mode as a radiation transfer heater or as a combination radiator and emitter, or may function with the principal energy transfer being in the emitter mode only.
Abstract:
By using a controlled arc-heated gas flow, material may be milled away from a substrate. By controlling the size of a gas flow aperture as well as other variables such as gas flow and arc current, small holes can be drilled into the substrate. Typically, these holes would have a diameter between 0.025 mm and 0.125 mm.In one embodiment, an arc made between an anode and cathode is placed above the work. A gas vortex is produced and is caused to pass through the arc, with the holes being drilled by the heated high-energy gas. Alternatively, the work may be used as the anode, with the gas flow carrying away material heated at the arc attachment point of the anode.The use of the arc-generated plasma gas vortex is particularly advantageous in the milling of multi-layer circuit boards.
Abstract:
The process is an arc jet CVD diamond deposition process with very low methane, less than 0.07%, and the addition of water. The resulting material has is characterized by a narrow Raman peak, a relatively large lattice constant, and a charge carrier collection distance of at least 25 microns. Also disclosed is a particle detector device which makes use of the diamond material according to the invention.
Abstract:
The substrate in a plasma jet deposition system is provided with structural attributes, such as apertures and/or grooves, that facilitate efficient deposition. Groups of substrates are arranged with respect to the plasma beam in a manner which also facilitates efficient deposition. In addition to increasing the portion of the plasma beam volume which contacts the substrate surface or surfaces, it is advantageous to provide for the efficient evacuation of spent fluids away from the substrate so that fresh plasma containing the operative species can easily and continuously contact the substrate surface.
Abstract:
A multi-layer diamond film is grown by d.c. arc assisted plasma deposition. A series of layers are deposited on each other by periodically back-etching the surface and renucleating during deposition. There may also be deposited a thin layer of non-diamond carbon material between the diamond layers, but no other non-carbon material. Renucleation is controlled by varying the proportion of methane to hydrogen in the feed gases, by temperature cycling of the substrate, or by inducing modal changes in the arc.
Abstract:
A heater/emitter for a rocket engine assembly utilizes a resistance heated wire coil or coils which may also function as a cathode emitter or as a thermal driver for an auxiliary emitter. This heater/emitter may if desired be formed into a bifilar and may be supported by the wire lead itself or by isolated supports. The power leads are located in a lead channel and feature an overwrapping of similar wire material which reduces the internal resistance heating of the lead to increase the electrical conductivity of the supporting lead and increase the thermal conduction thereof to establish a cooler and structurally-stronger lead. A plurality of radiation discs or shields are spaced along the leads to further minimize energy losses from the heater out of the lead channel. The heater/emitter itself is enclosed, except for the lead channel, by a heat exchanger housing. The function of this housing is to accept energy from the hot heater coil and in turn transfer that energy to a fluid flowing through the heat exchanger. Power is transferred from the hot heater coil to the heat exchanger firstly by means of radiation heat transfer, and secondly by impingement of thermionic electrons accelerated thru a potential imposed between the emitter and the heat exchanger. This packaging approach permits radiation transfer efficiencies, from coil to heat exchanger, of 90 to 95 percent. The thermionic electron emission and acceleration efficiency approaches 100 percent. The dual energy transfer mode permits single device operation over wider power ranges and thrust levels than would be permitted by single mode devices. The device may be operated in the single mode as a radiation transfer heater or as a combination radiator and emitter, or may function with the principal energy transfer being in the emitter mode only.
Abstract:
Method and apparatus for micro-arc brazing and welding of metal to metal or ceramic. The control of arc heat flux density is accomplished by controlling the ambient gas pressure and providing an argon, argon/5% hydrogen or other inert gas atmosphere. The discharge current is controlled so as to provide an arc which is operable at 100 microamps to 20 amps.Prior to welding or brazing, the work is cleaned by high frequency electrical discharge cleaning techniques using high energy ions from either the ambient gas or from an electrode. By providing a small amount of DC during the high frequency discharge a "tinning" capability is established.The welding or brazing may be formed in a closed chamber so that arc stabilization can be accomplished.
Abstract:
A multi-layer diamond film is grown by d.c. arc assisted plasma deposition. A series of layers are deposited on each other by periodically back-etching the surface and renucleating during deposition. There may also be deposited a thin layer of non-diamond carbon material between the diamond layers, but no other non-carbon material. Renucleation is controlled by varying the proportion of methane to hydrogen in the feed gases, by temperature cycling of the substrate, or by inducing modal changes in the arc.
Abstract:
The substrate in a plasma jet deposition system is provided with structural attributes, such as apertures and/or grooves, that facilitate efficient deposition. Groups of substrates are arranged with respect to the plasma beam in a manner which also facilitates efficient deposition. In addition to increasing the portion of the plasma beam volume which contacts the substrate surface or surfaces, it is advantageous to provide for the efficient evacuation of spent fluids away from the substrate so that fresh plasma containing the operative species can easily and continuously contact the substrate surface.