Abstract: Ion erosion of grids is reduced in an ion thruster with a multiple-grid ion-optics system. The thruster has an array of aperture sets in which aperture areas change in a perimeter region of the array. In one ion-optics system embodiment, a screen aperture area is reduced and a decelerator aperture area is increased in aperture sets that are proximate to the perimeter of the array. Prototype tests of this embodiment have illustrated significant reduction of ion erosion.

Abstract: A workpiece is heated by first forming an ionized gas plasma around the workpiece. A positive potential is applied to the workpiece to accelerate electrons from the plasma into the workpiece. The workpiece is uniformly surface heated by the energy directed into the workpiece by the electrons. The workpiece is cooled by providing a flow of a pressurized liquid material such as carbon dioxide having a triple point. The liquid material is expanded through a nozzle to form solid particles that contact the surface of the workpiece and remove heat from it by subliming.

Abstract: A plasma heating apparatus for heating a workpiece includes a chamber of sufficient size to receive a workpiece therein and a source of a reduced gas pressure within the chamber of from about 0.01 to about 100 millitorr. The plasma heating apparatus further includes a plasma source of an enveloping plasma. Optionally, a workpiece voltage may be applied between the workpiece and the wall of the chamber, and a source of a reactive gas can be provided to backfill the chamber, and radiant heaters can be provided to independently heat portions of the workpiece. In operation, the plasma source produces a plasma that surrounds and heats the workpiece. The plasma and the heating of the workpiece are tailored to achieve controllably uniform or nonuniform heat treatment and/or surface treatment of the workpiece.

Abstract: A workpiece is heated by first forming an ionized gas plasma around the workpiece. A positive potential is applied to the workpiece to accelerate electrons from the plasma into the workpiece. The workpiece is uniformly surface heated by the energy directed into the workpiece by the electrons. The workpiece is cooled by providing a flow of a pressurized liquid material such as carbon dioxide having a triple point. The liquid material is expanded through a nozzle to form solid particles that contact the surface of the workpiece and remove heat from it by subliming.

Abstract: Diamondlike carbon is deposited on a deposition substrate in a deposition apparatus that can be evacuated and backfilled with a carbonaceous gas. A plasma is generated in the gas by heating a filament within the chamber to produce electrons, and positively biasing the filament with respect to the deposition chamber wall to accelerate the electrons into the carbonaceous gas. The carbonaceous gas dissociates and ionizes in the resulting plasma to produce positively charged carbon ions. A deposition substrate within the chamber is negatively biased with respect to the deposition chamber wall, accelerating the carbon ions so that they are deposited onto the surface of the substrate.

Abstract: A high dose rate, high impedance plasma ion implantation method and apparatus to apply high voltage pulses to a target cathode within an ionization chamber to both sustain a plasma in the gas surrounding the target, and to implant ions from the plasma into the target during at least a portion of each pulse. Operating at voltages in excess of 50 kV that are too high for the reliable formation of a conventional glow discharge, the plasma is instead sustained through a beam-plasma instability interaction between secondary electrons emitted from the target and a background pulsed plasma. The voltage pulses are at least about 50 kV, and preferably 100 kV or more. Pulse durations are preferably less than 8 microseconds, with a frequency in the 50-1,000 Hz range. The preferred gas pressure range is 1.times.10.sup.-4 -1.times.10.sup.

Abstract: A plasma ion implantation apparatus includes a vacuum chamber that receives the object within its walls. The object is supported upon an electrically conductive base that is electrically isolated from the wall of the vacuum chamber. An electrically conductive enclosure is positioned between the object and the wall of the vacuum chamber and supported upon the base. The enclosure is made of an electrically conductive material. A plasma source is positioned so as to create a plasma in the vicinity of the object to be implanted. A voltage source applies an electrical voltage to the base and thence the enclosure relative to the wall of the vacuum chamber. Secondary electrons emitted from the object during implantation are reflected back into the plasma by the enclosure, reducing X-ray production and improving plasma efficiency.

Abstract: Wear-resistant titanium nitride coatings onto cast iron and other carbon-containing materials is enhanced by means of a new surface preparation and deposition process. The conventional pre-deposition surface cleaning by Ar.sup.+ ion bombardment is replaced by a hydrogen-ion bombardment process which cleans the substrate surface by chemical reaction with minimal sputtering and simultaneously removes graphite present on the cast iron surface. Removal of the graphite significantly improves the wear resistance of titanium nitride, since the presence of graphite causes initiation of wear at those sites. Hydrogen ion bombardment or electron bombardment may be used to heat the substrate to a chosen temperature. Finally, titanium nitride is deposited by reactive sputtering with simultaneous bombardment of high-flux Ar.sup.+ ions from an independently generated dense plasma.

Abstract: Plasma processing treatment characteristics of an object are determined nondestructively, prior to plasma processing the object, by placing an indicator layer over at least a portion of the plasma processing surface of the object, so as to generally conform to the shape of the surface. An electrically conductive grid is placed over the indicator layer, and made electrically common with the object. The indicator layer is implanted through the conductive grid, and changes properties responsive to the plasma processing treatment. The implanted indicator layer is thereafter analyzed to determine the treatment characteristics of the indicator layer. Plasma processing spatial distribution and total dosage are determined nondestructively from this information and used to establish the plasma processing program for the object and adjust the plasma processing apparatus as needed.

Abstract: An object (30) is plasma processed by placing an electrically conducting grid (34) over all or a portion of the surface (32) of the object (30) so that the grid (34) generally follows the contours of the surface (32) but is displaced outwardly from the surface (32). Ions or electrons from a plasma surrounding the object (30) are accelerated into the surface (32) of the object (30) using as a processing driving force an electrical potential applied to the electrically conducting grid (34). The use of a contoured conducting grid (34) allows plasma processing of large, electrically nonconducting objects and objects having sharp surface features or recesses.

Abstract: Plasma-enhanced magnetron-sputtered deposition (PMD) of materials is employed for low-temperature deposition of hard, wear-resistant thin films, such as metal nitrides, metal carbides, and metal carbo-nitrides, onto large, three-dimensional, irregularly shaped objects (20) without the requirement for substrate manipulation. The deposition is done by using metal sputter targets (18) as the source of the metal and immersing the metal sputter targets in a plasma (16) that is random in direction and fills the deposition chamber (12) by diffusion. The plasma is generated from at least two gases, the first gas comprising an inert gas, such as argon, and the second gas comprising a nitrogen source, such a nitrogen, and/or a carbon source, such as methane. Simultaneous with the deposition, the substrate is bombarded with ions from the plasma by biasing the substrate negative with respect to the plasma to maintain the substrate temperature and control the film microstructure.

Abstract: A high dose rate, high impedance plasma ion implantation method and apparatus to apply high voltage pulses to a target cathode within an ionization chamber to both sustain a plasma in the gas surrounding the target, and to implant ions from the plasma into the target during at least a portion of each pulse. Operating at voltages in excess of 50 kV that are too high for the reliable formation of a conventional glow discharge, the plasma is instead sustained through a beam-plasma instability interaction between secondary electrons emitted from the target and a background pulsed plasma. The voltage pulses are at least about 50 kV, and preferably 100 kV or more. Pulse durations are preferably less than 8 microseconds, with a frequency in the 50-1,000 Hz range. The preferred gas pressure range is 1.times.10.sup.-4 -1.times.10.sup.

Abstract: An article (40), such as a piece of manufacturing tooling, is modified prior to use by treating a portion of its surface (38) to be worn so that the treated surface worn more than a preselected amount has a different appearance than the treated surface worn less than the preselected amount, using a treatment process in which the treated surface is at least as wear resistant as the untreated surface. In one approach, the surface (38) is treated by implanting ions to a preselected depth. The ions are chosen so that the substrate has a different color at depths less than the preselected depth than does the substrate at depths greater than the preselected depth. After wear, the treated surface is visually inspected for color variations that indicate wear to more than the preselected depth. The surface treatment can also be accomplished by ion implanting or ion beam mixing a previously deposited surface coating.

Abstract: An object which is to be implemented with ions is enclosed in a container. A plasma is generated in a chamber which is separate from, and opens into the container. The plasma diffuses from the chamber into the container to surround the object with uniform density. High voltage negative pulses are applied to the object, causing the ions to be accelerated from the plasma toward, and be implanted into, the object. Line-of-sight communication between a plasma generation source located in the chamber and the object is blocked, thereby eliminating undesirable effects including heating of the object by the source and transfer of thermally discharged material from the source to the object. Two or more chambers may be provided for generating independent plasmas of different ion species which diffuse into and uniformly mix in the container. The attributes of the different plasmas may be individually selected and controlled in the respective chambers.

Abstract: An object (14) which is to be implanted with ions is enclosed in a container (12). A plasma (44) is generated in a chamber (26) which is separate from, and opens into the container (12). The plasma diffuses from the chamber (26) into the container (12) to surround the object (14) with uniform density. High voltage negative pulses are applied to the object (14), causing the ions to be accelerated from the plasma (44) toward, and be implanted into, the object (14). Line-of-sight communication between a plasma generation source (30) located in the chamber (26) and the object (14) is blocked, thereby eliminating undesirable effects including heating of the object (14) by the source (30) and transfer of thermally discharged material from the source (30) to the object (14). Two or more chambers (26,34) may be provided for generating independent plasmas (44,46) of different ion species which diffuse into and uniformly mix in the container (12).

Abstract: A capacitor is charged to a high potential or voltage from a power source. A plasma switch, preferably a CROSSATRON modulator switch, is periodically closed and opened to discharge the capacitor into an object for implantation with ions from a plasma in a plasma source ion implantation apparatus. The periodic discharge results in the application of high voltage negative pulses to the object, causing ions from the plasma to be accelerated toward, and implanted into the object. A pulse transformer is preferably provided between the plasma switch and capacitor, and the object to step up the voltage of the pulses and enable the plasma switch to operate at lower voltage levels. The plasma switch enables high duty factor and power operation, and may be combined with arc detection and suppression circuitry to prevent arcing between the object and plasma.

Abstract: A molecular beam epitaxy (MBE) growth method and apparatus is disclosed which achieves a significantly improved sticking coefficient for materials like Hg upon a substrate, and thus a higher efficiency. A highly ionized, low pressure plasma is formed consisting of a mixture of ions of one substance of a compound to be epitaxially grown, neutral particles of the substance and electrons, and also preferably both ionization and excitation radiation. The plasma is directed onto a substrate together with a flux of the other substance in the compound; the flux can be in the form of either a vapor, or a second plasma. Radiation assisted epitaxial growth for Hg compounds in which ionization and excitation radiation are formed from Hg vapor and used to assist epitaxial growth with neutral Hg particles is also described. The plasma is formed in a special discharge chamber having a hollow cathode with an emissive-mix-free cathode insert.

Abstract: The resistance to wear-induced failures during forming operations of non-ferrous die tooling materials, such as epoxy-based and zinc-based materials, is improved by treating the surface of the die tooling. In one approach, the surface of an organic-containing or metallic substrate is coated with a silicon-modified organic materials and then implanted with ions of an inert gas to transform the organic material to a silicon carbide-rich layer. In the other, nitrogen ions are implanted into the surface of a zinc-based alloy.

Abstract: A molecular beam epitaxy (MBE) growth method and apparatus is disclosed which achieves a significantly improved sticking coefficient for materials like Hg upon a substrate, and thus a higher efficiency. A highly ionized, low pressure plasma is formed consisting of a mixture of ions of one substance of a compound to be epitaxially grown, neutral particles of the substance and electrons, and also preferably both ionization and excitation radiation. The plasma is directed onto a substrate together with a flux of the other substance in the compound; the flux can be in the form of either a vapor, or a second plasma. Radiation assisted epitaxial growth for Hg compounds in which ionization and excitation radiation are formed from Hg vapor and used to assist epitaxial growth with neutral Hg particles is also described. The plasma is formed in a special discharge chamber having a hollow cathode with an emissive-mix-free cathode insert.

Abstract: A solid electrolyte ion source has an emitting tip which is small enough to concentrate an elecric field from an extraction plate and thereby significantly increase the extracted current density compared to prior solid electrolyte sources. The source is heated to a temperature sufficient to induce a thermionic ion emission from the tip. The ion emission can be varied independent of the extraction field by varying the degree of heating, thereby preserving a constant focused ion beam spot size during changes of beam brightness. The tip preferably has a radius in the approximate range of 1-10 microns. The source can be used for ion-microprobe surface analysis and micro-circuit fabrication applications previously unavailable with solid electrolyte sources.