Abstract: A continuous precision forming device and process for an amorphous alloy is provided. By means of the device, when a melting platform with an alloy melt is rotated from the melting position to a position just below the forming mould (9), temperature of the alloy melt can be in the range of the overcooled liquid zone temperature of the alloy melt, and then a loading rod (7) drives the forming mould (9) to proceed with pressing forming. According to the process, press-forming is carried out in a certain temperature interval in the amorphous alloy melt solidification process, and the heating, cooling, solidification and forming in the forming process are coordinated, such that continuous forming of the amorphous alloy is achieved.

Abstract: A method for manufacturing a formed glass includes using a heating apparatus. The heating apparatus includes a heating element and a heat reservoir having a transmittance of 50% or more in a wavelength of 0.5 ?m to 2.5 ?m. The heat reservoir is arranged between the heating element and a glass substrate as an object to be heated. The glass substrate is heated with the heating element, and the glass substrate is formed into a desired shape.

Abstract: A cover glass article includes a glass body having a three-dimensional shape, an inside surface, and an outside surface. Each of the inside and outside surfaces has a surface roughness (Ra) less than 1 nm and is free of indentations having diameters larger than 150 ?m.

Abstract: An apparatus and continuous stable process for producing multicrystalline silicon ingots with large cross-sections by an induction method, by maintaining surface temperature of the ingot at the output of the crucible within the range of 900-1150° C., and by heating the ingot at the output of the upper zone of the controlled cooling compartment to a temperature of 1200-1250° C., followed by cooling of the ingot at a rate of no more than 10° C./cm.

Abstract: A process for reinforcing a glass-ceramic article, into which a maximum tension is introduced beneath the surface of the glass-ceramic, advantageously in proximity to said surface. The invention also relates to an enamel that can be used for this reinforcement, this enamel being formed from a glass frit having the following composition, the proportions being expressed as weight percentages: SiO2 50-66% MgO 3-8% Na2O ?7-15% K2O 0-3% Li2O ?0-12% CaO ?0-10% BaO ?0-15% Al2O3 0-3% ZrO2 0-3% ZnO 0-5% B2O3 0-8% the sum of the alkaline-earth metal oxides CaO+BaO moreover being between 8 and 15%, and the sum of the alkali metal oxides Na2O+K2O+Li2O moreover being between 7 and 20%. The reinforced glass-ceramics obtained by the process.

Abstract: A method of producing glass-ceramic includes providing a glass made from a glass composition comprising LiO2, Al2O3, SiO2, and at least one nucleating agent. The glass is disposed in a microwave processing chamber. Microwaves are then selectively delivered into the microwave processing chamber at varying frequencies to induce different distributions of microwave fields in the glass. The glass is nucleated and crystallized while under the influence of the induced microwave fields.

Abstract: An apparatus for manufacturing tempered glass. A transportation unit transports a glass substrate that is intended to be tempered. An ionizer ionizes alkali oxides in the glass substrate by radiating energy onto the glass substrate. A dielectric heating unit increases the temperature of the inner portion of the glass substrate in which the alkali oxides are ionized by the ionizer.

Abstract: Methods for machining glass structures may be performed on fusion-drawn glass laminates having a core layer interposed between a first cladding layer and a second cladding layer. The core layer may be formed from a core glass composition having a core photosensitivity, the first cladding layer may be formed from a glass composition having a photosensitivity different from the core photosensitivity, and the second cladding layer may be formed from a glass composition having a photosensitivity different from the core photosensitivity. At least one of the core layer, the first cladding layer, and the second cladding layer is a photomachinable layer. The methods may include exposing a selected region of a photomachinable layer in the fusion-drawn laminate to ultraviolet radiation; heating the glass structure until the selected region crystallizes; and removing the crystallized material selectively from the photomachinable layer.

Abstract: Provided is a glass substrate with a sealing material layer, including a sealing material layer formed by sintering a sealing material, in which: the sealing material includes at least inorganic powder; the inorganic powder includes glass powder and a refractory filler; the content of refractory filler in the inorganic powder is 10 to 35 vol %; and the sealing material layer has a surface roughness Ra of less than 0.5 ?m.

Abstract: The invention relates to glass ceramics, which show high strength, high translucency, high chemical stability and which are still mechanically processible. The invention further refers to a method for producing a dental restoration comprising such glass or glass ceramic as well as the dental restoration itself.

Abstract: A method for the production of a mirror element (10) that has a reflective coating (10a) for the EUV wavelength range and a substrate (10b). The substrate (10b) is pre-compacted by hot isostatic pressing, and the reflective coating (10a) is applied to the pre-compacted substrate (10b). In the method, either the pre-compacting of the substrate (10b) is performed until a saturation value of the compaction of the substrate (10b) by long-term EUV irradiation is reached, or, for further compaction, the pre-compacted substrate (10b) is irradiated, preferably homogeneously, with ions (16) and/or with electrons in a surface region (15) in which the coating (10a) has been or will be applied. A mirror element (10) for the EUV wavelength range associated with the method has a substrate (10b) pre-compacted by hot isostatic pressing. Such a mirror element (10) is suitable to be provided in an EUV projection exposure system.

Abstract: Certain example embodiments of this invention relate to apparatuses for sealing the tips of pump-out tubes of vacuum insulating glass (VIG) units, and/or associated methods. In certain example embodiments, a laser source used in sealing the pump-out tube is thermally insulated from the VIG unit and emits a laser beam through one or more windows in an oven towards a mirror located therein. The mirror is located so as to redirect the laser beam onto the pump-out tube to thereby seal it. For instance, a substantially horizontal laser beam emitted from a laser source located outside the oven enters into the oven through one or more windows and is reflected by a mirror towards the pump-out tube to be sealed. The repositioning of the laser source advantageously can change its effective focal length and/or the location of the laser beam, e.g., because of the fixed location of the mirror.

Abstract: Process for preparing glass-ceramic body including the steps of providing a basic glass body and subjecting the basic glass body to a thermal treatment whereby a crystalline phase embedded in a glass matrix is formed. The basic glass body is made of a composition comprising 65 to 72 wt-% SiO2, at least 10.1 wt-% Li2O and at least 10.1 wt-% Al2O3 based on the total weight of the composition, the proportion of Li2O to Al2O3 being from 1:1 to 1.5:1. The thermal treatment involves a nucleation step followed by several crystallization steps at different temperatures, whereby at least two different crystalline phases are formed.

Abstract: A method to form quartz glass ingots of ultra low contamination and defect levels by firing a high-purity quartz form as the feedstock, wherein the quartz glass ingot is free-formed on a platen rotating concentrically with the feedstock quartz article.

Abstract: Raised features are formed on a transparent substrate having absorption of less than about 20% within a processing wavelength range. A portion of the substrate is irradiated with a light beam to increase the absorption of the irradiated portion of the substrate. Continued irradiation causes local heating and expansion of the substrate so as to form a raised feature on the substrate surface.

Abstract: Disclosed is an electromagnetic casting method of polycrystalline silicon which is characterized in that polycrystalline silicon is continuously cast by charging silicon raw materials into a bottomless cold mold, melting the silicon raw materials using electromagnetic induction heating, and pulling down the molten silicon to solidify it, wherein the depth of solid-liquid interface before the start of the final solidification process is decreased by reducing a pull down rate of ingot in a final phase of steady-state casting. By adopting the method, the region of precipitation of foreign substances in the finally solidified portion of ingot can be reduced and cracking generation can be prevented upon production of a polycrystalline silicon as a substrate material for a solar cell.

Abstract: When fusing glass members 104, 105 together by irradiating a glass layer 203 with a laser beam L2 along a region R to be fused, a crystallized area 108 formed in the glass layer 203 is taken as an irradiation-initiating point and an irradiation-ending point. Since the crystallized area 108 exhibits a laser absorptance lower than that of the glass layer 203 here, the glass layer 203 is gradually heated when the laser beam L2 is moved along the region R to be fused from the irradiation-initiating point, while the glass layer 203 is gradually cooled when the laser beam L2 is moved along the region R to be fused to the irradiation-ending point. This can prevent residual stresses from occurring in a part including the irradiation-initiating point and irradiation-ending point of the laser beam L2.

Abstract: This invention provides an inexpensive and rapid method for fabricating a high-anisotropic-etch ratio, shaped glass structures using a novel photosensitive glass composition. Structures of the photosensitive glass may include micro-channels, micro-optics, microposts, or arrays of hollow micro-needles. Furthermore, such shaped glass structures can be used to form a negative mold for casting the shape in other materials.

Abstract: The invention is directed to a method and apparatus for joining together pieces of low thermal expansion glass to form parts that can be used in the manufacturing of mirror blanks. The parts are then used as a basis for the fabrication, using the method described herein, of hexagon sub-assemblies that would then be joined for assembly into mirror blanks.

Abstract: The invention seeks to increase the sealing property and the reliability of an electronic device by suppressing cracks, fractures and the like of a glass substrate at the time of laser sealing. A glass substrate 3 has a sealing region. On the sealing region, a sealing material layer 5 comprising a glass material for sealing containing a low-expansion filler and a laser absorbent is provided. The glass material for sealing contains no low-expansion filler particles having particle sizes exceeding the thickness T of the sealing material layer 5 and contains low-expansion filler particles having particle sizes within a range of from 0.5T to 1T based on the thickness T of the sealing material layer 5 in a volume ratio of from 0.1 to 50%. Such a glass substrate 3 and a glass substrate 2 having an element-formed region provided with an electronic element are laminated, and the sealing material layer 5 is irradiated with a laser light 6 and melted to bond the glass substrates 2 and 3.

Abstract: The process of making the glass-ceramic includes ceramicizing a starting glass at a heating or cooling rate during the ceramicization of at least 10 K/min, so that the glass-ceramic contains at least 50% by volume of ferroelectric crystallites with a maximum diameter of from 20 to 100 nm and not more than 10% by volume of nonferroelectric crystallitesis. The glass ceramic produced by the process contains no pores or not more than 0.01% by volume of the pores and a value of e?·V2max of the glass-ceramic is at least 20 (MV/cm)2, wherein e? is the dielectric constant at 1 kHz and Vmax is the breakdown voltage per unit thickness. The ferroelectric crystallites preferably have a perovskite structure and are composed of substantially pure or doped BaTiO3 and/or BaTi2O5.

Abstract: This invention provides an inexpensive and rapid method for fabricating a high-anisotropic-etch ratio, shaped glass structures using a novel photosensitive glass composition. Structures of the photosensitive glass may include micro-channels, micro-optics, microposts, or arrays of hollow micro-needles. Furthermore, such shaped glass structures can be used to form a negative mold for casting the shape in other materials.

Abstract: A method for producing thin silicon rods using a floating zone crystallization process includes supplying high frequency (HF) current to a flat induction coil having a central opening, a plurality of draw openings and a plate with a slot as a current supply of the HF current so as to provide a circumfluent current to the central opening. An upper end of a raw silicon rod is heated by induction using the flat induction coil so as to form a melt pool. A thin silicon rod is drawn upwards through each of the plurality of draw openings in the flat induction coil from the melt pool without drawing a thin silicon rod through the central opening having the circumfluent current.

Abstract: A method for recharging a crucible with polycrystalline silicon comprises adding flowable chips to a crucible used in a Czochralski-type process. Flowable chips are polycrystalline silicon particles made from polycrystalline silicon prepared by a chemical vapor deposition process, and flowable chips have a controlled particle size distribution, generally nonspherical morphology, low levels of bulk impurities, and low levels of surface impurities. Flowable chips can be added to the crucible using conventional feeder equipment, such as vibration feeder systems and canister feeder systems.

Abstract: A method for producing an airtight container includes preparing an assembly having a first substrate and a frame member, the first substrate having an electron-emitting element formed on a first surface thereof, the frame member mounted on the first surface outside an area where the electron-emitting element is formed; forming a temporary assembly having the assembly and a second substrate by bringing the second substrate into contact with the frame member via a joining member such that an inner space is formed; melting the joining member by irradiating the joining member with a laser beam transmitted through the second substrate; and solidifying the melted joining member. The laser beam is applied such that an incident direction at an irradiation position on the joining member does not include components toward the interior of the frame member while the laser beam moves relative to the temporary assembly.

Abstract: This invention is related to obtaining multicrystalline silicon using induction method. The method comprises melting and casting of a pool in the form of a melting space, crystallization of a multicrystalline silicon ingot, and its controlled cooling by means of a heating equipment set. After the pool melting and casting is terminated, crystallization of the remaining part of the multicrystalline silicon ingot is finished along with the controlled cooling of the whole ingot; the ingot is then removed together with a movable bottom and the heating equipment set; and its controlled cooling continues. At the same time, another heating equipment set is supplied to the vacated place with another movable bottom; then the new movable bottom is moved into the water-cooled crucible; and the process steps are repeated in order to produce the next ingot. The method is implemented using an apparatus that additionally includes a platform installed in the controlled cooling compartment and designed to revolve on its axis.

Abstract: Disclosed is a method of producing a barium-titanium-based ferroelectric glass using a containerless solidification process, such as an electrostatic levitation process or a gas levitation process, which comprises the steps of levitating a sample 1 of a barium-titanium-based compound by a levitating force of compressed air, heating the sample up to a temperature greater than its melting point (1330° C.) by about 100° C. to allow the sample to be molten, and, after maintaining the molten state for a given time period (at least several second), quenching the sample from a given temperature range (1400 to 1000° C.) at a cooling rate of about 103 K/sec, so as to allow the sample to be solidified while inhibiting nucleation and mixing of impurities from a container. The present invention makes it possible to provide a glass exhibiting an unprecedented, extremely large permittivity.

Abstract: The invention proposes a method for producing glass ceramics which is particularly well suited as light conversion material, especially for down conversion. One initially produces a starting glass, containing (on an oxide basis) 5-50% by weight of SiO2, 5-50% by weight of Al2O3 and 10-80% by weight of at least one oxide selected from the from the group formed by Y2O3, Lu2O3, Sc2O3, Gd2O3, Yb2O3, Ce2O3, as well as 0.1-30% by weight of at least one oxide selected from the group formed by B2O3, Th2O3, and oxides of the lanthanoids, except Lu2O3, Gd2O3, Yb2O3, Ce2O3. Thereafter, the material is heated up for ceramization at a heating rate of at least 100 K/min to a temperature in the range of between 1000° C. to 1400° C. until crystallites are formed that contain a garnet phase. Thereafter, the material is cooled down to room temperature. Alternatively, controlled cooling-down from the molten state is possible.

Abstract: When fusing glass members 104, 105 together by irradiating a glass layer 203 with a laser beam L2 along a region R to be fused, a crystallized area 108 formed in the glass layer 203 is taken as an irradiation-initiating point and an irradiation-ending point. Since the crystallized area 108 exhibits a laser absorptance lower than that of the glass layer 203 here, the glass layer 203 is gradually heated when the laser beam L2 is moved along the region R to be fused from the irradiation-initiating point, while the glass layer 203 is gradually cooled when the laser beam L2 is moved along the region R to be fused to the irradiation-ending point. This can prevent residual stresses from occurring in a part including the irradiation-initiating point and irradiation-ending point of the laser beam L2.

Abstract: A method of hot forming of at least a part of an article is provided. The article includes a material selected from the group consisting of transparent and semitransparent materials. The method includes semi-homogeneously heating at least a part of the article by radiation and forming the heated part of the article.

Abstract: The present invention describes a composition, method and article for a photomachinable glass having a coefficient of thermal expansion from less than 6×10?6/° C. in the temperature range of 0° C. to 300° C. The photomachinable glass composition is a low expansion glass having an amorphous glass phase and crystalline phases selected from the group consisting of spudomene and lithium disilicate.

Abstract: The balance spring is made from a photostructurable glass plate by UV irradiation, thermal treatment and etching, said glass having a Young's modulus thermal coefficient CTE0. The value CTE0 of selected zones of the balance spring are altered to a value CTEi by UV irradiation through one or several masks, possibly completed by a thermal treatment.

Abstract: This invention relates to a process for the production of high purity elemental silicon by reacting silicon tetrachloride with a liquid metal reducing agent in a two reactor vessel configuration. The first reactor vessel is used for reducing the silicon tetrachloride to elemental silicon, resulting in a mixture of elemental silicon and reducing metal chloride salt while the second reactor vessel is used for separating the elemental silicon from the reducing metal chloride salt. The elemental silicon produced using this invention is of sufficient purity for the production of silicon photovoltaic devices or other semiconductor devices.

Abstract: The coefficient of absorption of a pre-selected region of a glass sheet is preferentially increased. The glass sheet may thereafter be sealed to a substrate using a sealing laser. In one embodiment, the coefficient of absorption sheet is increased by irradiating the glass sheet at a wavelength of about 248 nm, preferably through a mask, to produce an irradiated pattern on the glass sheet having a pre-determined shape. The glass sheet is then heat treated, placed over a substrate and sealed to the substrate by exposing the irradiated pattern to a sealing laser light having a wavelength in the range between about 355 nm and 532 nm to produce a glass envelope. The method disclosed herein is useful, inter alia, for manufacturing electro-luminescent devices, such as light emitting diodes (LEDs) and in particular organic light emitting diodes (OLEDs).

Abstract: A nonlinear optical crystal having a chemical formula of YiLajAlkB16O48, where 2.8?i?3.2, 0.8?j?1.2, i and j sum to about four, and k is about 12 is provided. The nonlinear optical crystal is useful for nonlinear optical applications including frequency conversion. Nonlinear optical crystals in a specific embodiment are characterized by UV blocking materials (e.g., some transition metals and lanthanides) at concentrations of less than 1,000 parts per million, providing high transmittance over portions of the UV spectrum (e.g., 175-360 nm).

Abstract: An inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass. Furthermore, the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals. These microneedle arrays can be used to extract fluids from plants or animals. Glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion.

Abstract: A method for the homogeneous heating of semitransparent and/or transparent glass and/or glass-ceramic articles using infrared radiation so that the glass and/or glass-ceramic articles undergo heat treatment at between 20 and 3000° C., notably at between 20 and 1705° C. Heating is achieved by a component of infrared radiation which acts directly on the glass and/or glass-ceramic articles and by a component of infrared radiation which acts indirectly on said glass and/or glass-ceramic articles. The radiation component indirectly acting on the glass and/or glass-ceramic articles accounts for more than 50% of total radiation output.

Abstract: The invention relates to a method of producing glass-ceramic parts and/or glass parts by deformation of a glass-ceramic blank and/or glass blank. The invention is characterized in that forming is carried out using infrared radiation.

Abstract: A method of heat treatment of glass materials and natural materials specifically of volcanic origin according to which the treated material is exposed to microwave radiation at a frequency range from 1 MHz to 10 GHz and temperature range from the ambient temperature to 1800° C. in a batch or continuous process. The glass or natural material subjected to a melting and/or refining process contains an inert additive elected from the group comprising carbides, nitrides or borides in an amount from 1 to 100 g preferably 5 to 50 g per 1 kg of the glass or natural material. The apparatus consists substantially of a microwave furnace comprising an outer shell (8.2) provided with a cover (10) and an inner shell (8.1) and at least one micro wave generator (1.1, 1.2, 1.3, 1.4) with double emission and total power from 0.1 to 1 kW per 1 kg of the treated material.

Abstract: An optical waveguide, such as an optical fiber, including a length of waveguide and at least one discrete longitudinal section having increased photosensitivity with respect to other portions of the waveguide.

Abstract: The invention relates to a method for ceramizing starting glass of glass-ceramics into glass-ceramics, comprising at least the following steps: 1.1 the starting glass is heated from an initial temperature T1 to a temperature T2 which is disposed above the glass transformation temperature TG at which crystallization nuclei are precipitated; 1.2 the glass is held at the temperature T2 for a period t2 for the precipitation of crystallization nuclei; 1.3 the glass is further heated to a temperature T3 at which a crystal phase grows on the nuclei formed following step 1.1 and 1.2; 1.4 the glass is held for a period t3 at a temperature T3 or heated during this period to a higher temperature T4 until the predetermined properties of the glass-ceramics have been reached; 1.5 the control of the temperature curve is performed with the help of a control loop comprising at least one temperature sensor for sensing the temperature and a heating unit as an actuator. The invention is characterized in that 1.

Abstract: A process for producing an SiO2 shaped body which is at least partially vitrified, wherein an amorphous, porous SiO2 green body is sintered or vitrified by contactless heating by means of radiation, while avoiding contamination to the SiO2 shaped body with foreign atoms, wherein the radiation used is the beam of a laser at a subatmospheric pressure below 1000 mbar.

Abstract: Glasses containing one or more rare-earth elements and one or more halides are disclosed including a region locally transformed into crystallized glass that comprises precipitated rare-earth element-containing halide crystals. Also disclosed are molded objects containing dispersed particles of glass containing one or more rare-earth elements and one or more halides and having a region within which the particles are transformed into crystallized glass particles. The crystallized region is invisible under usual light but can be detected using upconversion luminescence generated by irradiation with excitation laser light having a specific wavelength. Disclosed further are methods for preparing such locally crystallized glasses and molded objects, as well as methods for efficient detection of the crystallized region in such glasses or molded objects.

Abstract: A glass includes (a) a matrix containing a compound of at least one nonmetallic element; and (b) a particle selectively formed in the matrix. This particle is made of the at least one nonmetallic element. A process for producing such glass includes (a) providing a blank glass containing a compound of at least one nonmetallic element; (b) condensing a pulsed laser beam to a focal point in the blank glass such that a particle is selectively formed in the blank glass at a position corresponding to the focal point, the particle being made of the at least one nonmetallic element dissociated from the compound; and (c) moving the focal point in the blank glass to produce a pattern of the particle. The glass is suitable for optical functional elements.

Abstract: The invention concerns a device for the heating of glasses and/or glass ceramics, comprising one or more IR radiators. The invention is characterized in that the device comprises at least one filter element, which filters at least a portion of the long-wave IR radiation of the IR radiators, so that no long-wave IR radiation or only a small amount impinges on the one or more glass-ceramic and/or glass parts to be heated.

Abstract: A method for shifting the absorption peak wavelength in the wavelength range 900-1600 nm of an infrared radiation absorbing glass from less than 1100 nm to 1100 nm or longer without substantially changing the tint of the glass, comprising the step of irradiating with ultraviolet light of 400 nm or shorter at an energy density of 1.0×106 J/m2/hr or more to increase the content of FeO in the irradiated glass by reducing Fe (III) to Fe (II), the ultraviolet light irradiated glass thereby comprising 0.02 wt. % or more FeO in terms of Fe2O3. The glass to be irradiated comprises, in % by weight: 65 to 80% SiO2, 0 to 5% Al2O3, 0 to 10% MgO, 5 to 15% CaO, 10 to 18% Na2O, 0 to 5% K2O, 5 to 15% MgO+CaO, 10 to 20% Na2O+K2O, and 0 to 5% B2O3; 0.02% or more total iron oxide (T-Fe2O3) in terms of Fe2O3, 0 to 2.0% CeO2, 0 to 1.0% TiO2, 0 to 0.005% CoO, and 0 to 0.005% Se.

Abstract: A method of making a vehicle windshield or other window. An opaque layer (e.g., enamel or water-based) is applied to a glass sheet and then “fired” or cured. The opaque layer is preferably black or dark in color. Thereafter, the sheet with the opaque layer thereon is cut into a desired windshield shape, along a cutting line which extends through both the glass sheet and the opaque layer formed thereon. As a result, on the cut glass sheet the opaque layer extends all the way up to the peripheral edge thereof. In vehicle windshield embodiments, the cut sheet is laminated to another glass sheet via at least a polymer based interlayer in order to form the vehicle windshield.

Abstract: A film forming device in a substrate manufacturing apparatus a stage section on which a cassette storing a plurality of glass substrates is mounted. A treatment section for subjecting the substrate to a predetermined treatment is arranged to oppose the stage section. A washing section for washing the substrate is arranged near the stage section and the treatment section and deviated from a space between the stage section and the treatment section in a second direction crossing a first direction passing through the stage section and the treatment section. A transfer robot is arranged between the stage section and the treatment section. The transfer robot transfers the substrate between the stage section, treatment section, and washing section and loads the substrate, washed in the washing section, directly into the treatment section.

Abstract: Voltage is applied between electrodes (14a, 14b) under UV irradiation to perform a UV excitation poling, thereby producing microcrystal particles at a core unit (10a). Accordingly, second-order optical nonlinearity is developed at the core unit (10a) of an optical fiber (10). Under a high-temperature condition, a second-order optical nonlinearity can be imparted by a comparatively low-voltage UV excitation poling when a second-order optical nonlinearity decreases.

Abstract: Apparatus suitable for vitrifying nuclear waste comprises a tunable microwave cavity connected by a first wave guide to a source of microwave energy; cooling coils for cooling the exterior of the cavity; a hopper for loading particulate fusible material to the interior of the cavity; within the cavity a crucible made of melted and re-solidified fusible particulate material; an exit-chamber connected by a second waveguide to a second microwave source; and a pipe for supplying argon gas to the exit chamber so that a plasma torch can be generated. The separating of the crucible form the cavity walls by unmelted material gives significant advantages in case of cleaning and reduced energy consumption.