Abstract: A device for magnetic field-assisted simulation of zero-microgravity flame synthesis of nanoparticles includes a gradient magnetic field device, a combustor and a product collection device. The gradient magnetic field device is composed of two magnetic field devices arranged face to face. The combustor is located between the two magnetic field devices. The outlet of the combustor is vertically upward. The position is below the magnetic field center of the gradient magnetic field device. The body force acting on the flame and surrounding magnetic species thereof by the gradient magnetic field device counteracts the gravitational buoyancy lift effect, so that flame synthesis is carried out under a simulated zero/microgravity flame to prepare the nanoparticles. The device is able to use a gradient magnetic field to simulate the zero/microgravity flame on the ground to synthesize the nanoparticles under special flame characteristics, with reduced flame disturbance, improved stability, and no overheated region.

Abstract: The invention relates to a mould for the manufacturing of mould steels in an inert gas or a pressurized electro slag re-melting apparatus. The mould comprises a non-rectangular and non-circular inner copper sleeve having a width, w, of 1000-2500 mm and a thickness, t, of 700-1250 mm, wherein the short sides in the thickness direction of the copper sleeve at least partly have sections with curved surfaces and wherein the long sides in the width direction at least partly have sections with curved surfaces.

Abstract: Plant for melting metal materials comprising at least a heating unit (11) provided with a container (13) to contain the mainly metal materials and with at least an induction heating device (22) configured to heat the mainly metal materials contained in the container (13). The plant also comprises a transfer unit (25) disposed downstream of the heating unit (11) and configured to move, substantially continuously, the mainly metal solid materials exiting from the heating unit (11) to a melting furnace (12). The container (13) is provided with an aperture (16) through which the mainly metal material, heated and in a solid state, is discharged onto the transfer unit (25), and opening/closing members (17) are associated with the aperture (16), commanded by an actuator (19) and configured to open, close and choke the aperture (16) in order to regulate the delivery of the metal materials that is discharged onto the transfer unit (25).

Abstract: Graphite is produced from powder as a carbon source by means of a graphitization furnace. The graphitization furnace is comprised of: an electrically conductive crucible including a hollow configured to house the powder; an electrode including a columnar shaft and a head provided at an end of the shaft, the head having a shape selected from the group consisting of a sphere, a hemisphere, a column with a rounded edge, a cone, and a cone with a rounded tip; and a power source configured to apply electric current to the powder through the crucible and the electrode.

Abstract: Apparatus and process for heating and melting a material in a susceptor vessel are provided wherein phase synchronized ac voltage is supplied from a separate power source to each one of at least two induction coils in separate zones around the vessel. Power magnitude from each source to an induction coil is controlled by pulse width control of the source's output voltage. Output frequency from each source is either fixed or variable based upon the electrically conductive state of the material. Optional electromagnetic stirring is achieved by establishing a phase shift between the voltage outputs of the power supplies after the material in the susceptor vessel has melted.

Abstract: Thermoplastic pellitized materials are melted in gravity flow through coaxially oriented perforated cylindrical metal susceptors. The susceptors are equally energized by the interception of a common magnetic field formed by a high frequency powered inductor coil.

Abstract: An induction furnace includes a melting induction coil for inductively heating a pair of susceptors for melting particulate material falling freely in a free fall zone between the susceptors. A feeder having a rotatable hollow shaft with fingers extending therefrom breaks up the material, which falls onto a vibrating dispersion plate and then into the free fall zone. A preheating induction coil inductively heats a susceptor which radiates heat to particulate material moving over the dispersion plate. An adjustable gap between the feeder and dispersion plate controls material flow. A funnel collects falling molten material and directs it through a nozzle into a mold. Induction coils control melting within the funnel. One induction coil heats the nozzle and may be controlled to allow the nozzle to cool sufficiently to form a solid plug in the nozzle whereby molten material pools above the plug.

Abstract: An analytical induction furnace and method for combusting conductive sample materials (500) utilizing a crucible for holding a sample within the induction furnace. Less than one gram of accelerator material is then inserted into the crucible with the sample and the induction furnace is activated for a predetermined time period (503) for thoroughly combusting the sample and accelerator. In some instances, no accelerator is required with the sample at frequencies of approximately 4.5 MHz. The invention provides for the induction furnace that is actuated in an RF frequency range between 2-9 MHz with little to no accelerator for thoroughly melting the sample for use in an analytical instrument.

Abstract: A method for reducing oxidic slags and dusts possibly loaded with organics uses an inductively heatable coke bed extending in the axial direction and having a temperature gradient. Reaction gas is sucked off in an axial region of the coke bed between two induction bodies and metal regulus and slag melt are tapped on the lower end. An inductively heatable shaft furnace chargeable with a lumpy coke bed for the reduction of metallic slags is made of an electrically insulating refractory material, has an adjustable temperature gradient includes at least one cooled induction body on the head side, a suction connection in an axial region where the prevailing temperature exceeds the condensation point of the substances to be removed, located below the cooled induction body on the head side, and an opening for tapping metal regulars and slag melt is provided on the lower end of the furnace.

Abstract: An induction furnace capable of drawing large diameter preforms of up to 130 mm is described. The induction furnace has top and bottom chimneys surrounding the entire preform during operation of the furnace with an inert conditioning gas which is introduced into the top chimney and flows downward through the furnace body and bottom chimney without significant turbulence. A distributor ring inside the top chimney redirects flow from a circumferential direction to a downward direction. The top chimney also includes a resilient seal to releasably hold the top of the preform. The bottom chimney has a smoothly decreasing cross-sectional area preventing turbulence at the furnace exit. The furnace insulation is preferably a rigid self-supporting graphite cylinder. A method of drawing large diameter preforms either to an optical fiber or to a preform of smaller diameter using such a furnace is also described.

Abstract: Apparatus and methods of operation are provided for a cold-crucible-induction melter for vitrifying waste wherein a single induction power supply may be used to effect a selected thermal distribution by independently energizing at least two inductors. Also, a bottom drain assembly may be heated by an inductor and may include an electrically resistive heater. The bottom drain assembly may be cooled to solidify molten material passing therethrough to prevent discharge of molten material therefrom. Configurations are provided wherein the induction flux skin depth substantially corresponds with the central longitudinal axis of the crucible. Further, the drain tube may be positioned within the induction flux skin depth in relation to material within the crucible or may be substantially aligned with a direction of flow of molten material within the crucible. An improved head design including four shells forming thermal radiation shields and at least two gas-cooled plenums is also disclosed.

Abstract: The present invention relates to a silicon refining installation, having a cold sectorized induction crucible, having its internal wall lined with a refractory material.

Abstract: Apparatus and methods of operation are provided for a cold-crucible-induction melter for vitrifying waste wherein a single induction power supply may be used to effect a selected thermal distribution by independently energizing at least two inductors. Also, a bottom drain assembly may be heated by an inductor and may include an electrically resistive heater. The bottom drain assembly may be cooled to solidify molten material passing therethrough to prevent discharge of molten material therefrom. Configurations are provided wherein the induction flux skin depth substantially corresponds with the central longitudinal axis of the crucible. Further, the drain tube may be positioned within the induction flux skin depth in relation to material within the crucible or may be substantially aligned with a direction of flow of molten material within the crucible. An improved head design including four shells forming thermal radiation shields and at least two gas-cooled plenums is also disclosed.

Abstract: A substance 6 is located in a gradient magnetic field and held in a levitating state by a magnetic force produced by the gradient magnetic field. The substance 6 as such in the levitating state is heated and melted by ray or heat irradiation or by a resistance heater. Thereafter, the heating is stopped, and the substance 6 is cooled as such in the levitating state. Since the magnetic force realizes the microgravity field where the substance 6 is melted and cooled in the levitating state, the substance 6 is formed to an ideally spherical shape with an extremely smooth surface.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: An alloying system for a galvanized steel sheet, the alloying system using an induction heating coil, wherein an impedance matching apparatus is provided between the induction heating coil and a high frequency power source. The impedance matching apparatus comprises a matching transformer having a plurality of intermediate contact points for arbitrarily selecting a turn ratio, and a switching device for alternative changeover of the intermediate contact point, whereby even when the load impedance of the steel sheet varies, maximum power source output is obtained, such that an appropriate heating temperature necessary for forming an alloy layer of the steel sheet can be supplied.

Abstract: A system for thermomechanical characterization of material using an induction heating system capable of reaching a temperature of 3300.degree. C. in not more than 20 seconds. This fast heating device comprises induction coils laid out at least partly around the sample (21) and generating induced currents, a susceptor placed between the sample and induction coils to transform induced currents into heat radiation, a thermal protection shield placed between the induction coils and susceptor shield to protect the induction coils from hear radiation emitted by the susceptor and an insulation material globally surrounding the induction coils. The invention has utility in fields using new materials, such as in the aeronautical and automotive industries.

Abstract: A coreless induction furnace includes a vertical melting crucible defining a melting chamber having upper and lower chamber portions and at least two coils. A first one of the coils is disposed so as to surround the upper chamber portion and a second one of said coils is disposed so as to surround the lower chamber portion. The furnace also includes a single-phase load-commutated oscillation circuit converter, a plurality of capacitors and an electrical circuit system electrically connecting the coils, the capacitors and the converter. The electrical interconnection is such that the first one of the coils is electrically connected in series with a first one of the capacitors having a first capacitvie impedance to thereby present a first oscillation circuit, and the second one of the coils is electrically connected in series with a second one of the capacitors having a second capacitive impedance to thereby present a second oscillation circuit.

Abstract: A heating module for use in steel processing is provided. The module includes one or more gas heating zones and one or more induction heating coils intermixed among the gas heating zones. The modules are used to heat steel slabs to a consistent temperature throughout. Generally, the induction coils are used to increase the temperature of the slab, while the gas heating zones function to hold the slab at the increases temperature and to allow the heat to soak into the interior of the slab. The gas heating zones are generally lined with refractory material and include sufficient rollers to carry the steel slabs through the heating modules. The rollers are positioned in such a manner that the majority of the surface area of the roller is not within the interior of the gas heating zone at any one time. At least a segment of the floor of the gas heating zone is pivotable such that debris can be easily removed from the heating zone and such that the interior of the heating zone is easily accessed.

Abstract: An induction heating coil used in a floating zone melting method, characterized in that the path of a high-frequency current is controllable in the body surface of the coil and by the use of the coil a more uniform resistivity profile across a diameter is achieved as compared with those from the prior art. In the coil a second metal or alloy different in electric conductivity from a first metal or alloy of the coil is disposed in a predetermined place(s) to control the path of a high-frequency current, wherein the second metal or alloy has, for example, higher electric conductivity than the first metal or alloy and a long narrow and thin strip made of the second metal or alloy is disposed in such a manner that it meanders on the body surface of the coil between the outer and inner peripheries periodically.

Abstract: An electromagnetic levitator is disclosed, comprising: a plurality of longitudinal sections formed from a conducting material and arranged around a longitudinal axis. The longitudinal sections are connected to a power source such that when the levitator is in operation, current flowing through adjacent longitudinal sections creates opposing magnetic fields. The levitator has first and second ends defining a levitation zone therebetween. When alternating current is passed through the conductors, a levitation tunnel is formed in the levitation zone, with the levitation tunnel having zero magnetic flux density along its center and non-zero magnetic flux density at all other points.

Abstract: The fiber-drawing furnace includes a graphite tube positioned vertically, heated by induction, and subjected internally to an inert atmosphere, said tube internally defining a fiber-drawing chamber. In the furnace said graphite tube is a double-walled tube having an inner wall and an outer wall, its inner wall is porous and separates the fiber-drawing chamber from a peripheral chamber defined between the walls and subjected to a flow of inert gas which diffuses through said porous wall into said fiber-drawing chamber. Application to drawing down an optical-fiber preform.

Abstract: A high-frequency induction heating coil is provided which enables a semiconductor single crystal in the process of growth to incorporate impurities uniformly therein, permits ready adjustment of the heat distributing property, and precludes the discharge of electricity across a slit. The high-frequency induction heating coil comprises a pair of annular conductors 21 and 22, a pair of power source terminals 23a and 23b for feeding a high-frequency electric current to the pair of annular conductors 21 and 22, and a plurality of small coils 24a through 24f and 25a through 25f having the pair of annular conductors as opposite electrodes and projecting toward the axis of the pair of annular conductors extending from a first annular conductor 21 to a second annular conductor 22.

Abstract: In addition to a first driving device which moves only a lower crucible, and a first control device which controls the first driving device, a second driving device which changes the vertical relative position of an upper crucible and an induction coil, and a second control device which controls the second driving device are disposed, whereby the relative positions of the upper and lower crucibles and the induction coil can freely be changed. Consequently, the relative positions of the induction coil and the upper and lower crucibles can adequately be set in whole of the operation period from the initial operation stage to the final operation stage, in accordance with the position of a melting zone in the top portion of a material to be melted which grows as a result of continuously charging chips.

Abstract: A metal material such as scraps of metal is directly heated by electromagnetic induction, and the resulting molten metal is fed to a heatup zone where the molten metal is further heated to a required temperature. More specifically, the metal material to be melted, which has been charged into a heat and melt zone, is preheated and melted by an induction coil, and the molten metal is passed via a connection portion to the heatup zone, and is stored there. The thus accumulated molten metal is further heated by an induction coil to a necessary temperature. The molten metal is taken out of the furnace by opening a tap hole when this is desired. Various kinds of gases can be selectively introduced into the apparatus via an gas inlet. By keeping the tap hole in an open condition, the molten metal can be continuously taken out of the furnace. With the induction heating method which has heretofore enabled only an intermittent melting operation, the metal material can be continuously melted and taken out.

Abstract: In a melting crucible (3) a central bottom portion (27) is formed of a plurality of palisades (5) and is shaped so that the palisades together form a vessel or a pot (7) having a centrally disposed spout or outlet (8). Two independently powered induction coils (10, 11) are provided, one coil (10) externally surrounding the collar or upper part of the central bottom portion (27), and the other coil (11) externally surrounding the spout (8). The palisades (5) are separated from one another by individual gaps (6) running radially outwardly from the center, while the electromagnetic field of at least the upper coil (10) acts on the charge contained in the melting crucible through the gaps (6).

Abstract: Apparatus to float and melt particularly small pieces of high-melting point metal continuously while making the amount of meltable liquid metal greater than the capacity of a crucible. A conductive crucible having segments includes an upper cylindrical crucible portion and a lower closed-end crucible portion. An induction coil is arranged outside the upper crucible portion, whereas an induction coil is arranged below the induction coil. The lower crucible portion is in contact with the upper crucible portion and located on the inside of the induction coil at the initial melting stage. The lower crucible portion is lowered as a columnar metal grows and solidifies between molten metal and the lower crucible portion. A continuous feeder continuously feeds cold material. A molten metal surface thermometer and a molten metal surface level gauge are arranged above the crucible. The operation of the continuous feeder is regulated within a desired range of values of the molten metal surface thermometer.

Abstract: A plurality of segments 12 respectively formed of an electrically insulated conductive material such as copper or the like are disposed inside an induction coil 1 in the peripheral direction of the induction coil 1 to thereby construct a crucible 3. There is formed a small cylindrical hole 4 in the center of the bottom portion of the crucible 3. A magnetic flux is allowed to enter the crucible 3 from slits 15 respectively formed between the hole 4 and segments 12 and is then interlinked with an object to be heated. The slits 15 respectively defined by mutually adjoining segments 12 are arranged such that the width of the bottom portion thereof is greater than that of the cylindrical portion thereof. When the width of the slit in the bottom portion is increased, then a leakage flux to the crucible is increased which in turn increases a levitation force F.

Abstract: Wafers of silicon-on-insulator (SOI) produced by the zone melting recrystallization technique are known to exhibit warping and edge defects which prohibit their use in automated silicon wafer processing equipment. These deficiencies arise from excess heat buildup at the periphery of the wafer because the wafer edge acts as a barrier to heat transfer. Dissipation of heat from the edge by varying the heat dissipation efficiency of the environment about the periphery of the wafer allows wafers with substantially fewer defects to be produced.

Abstract: A crucible induction furnace is disclosed which is provided with a preventive measure against low melting point metals and having a crucible refractory within an induction coil in a barrel container, in which the crucible induction furnace comprises a coil protection member located between the crucible refractory and the induction coil and which includes at least one air-permeating portion. An air supply pipe is in communication with the air-permeating portion for supplying pressurized air to the crucible refractory. The air permeating portion is disposed to distribute pressurized air having a higher pressure adjacent to the bottom portion of the crucible refractory than to the upper portion of the crucible refractory.

Abstract: A vertical gradient freeze single crystal growing apparatus utilizing a direct monitoring furnace which is possible to obtain rapid high temperature heating and uniform temperature distribution by using direct monitoring furnace as a higher temperature part furnace provided with double quartz tube applied with gold thin film, and also capable of observing entire process of single crystal growing directly by naked eye.

Abstract: A composite susceptor for a radio frequency (RF) heated crystal growing furnace has a plurality of stacked electrically insulating and electrically conducting elements about the crucible area so that a proper temperature gradient is established and controlled.

Abstract: An apparatus for growing a monocrystalline body (30) from a polycrystalline feed rod (22) includes a heater (20) that is positioned to heat a short section of the polycrystalline rod (22) to create a molten zone (34). The heater (20) is formed to include a shaper (40) that contacts the polycrystalline rod (22) in the molten zone (34) and has a hole (46) to allow flow in the molten zone (34) between the polycrystalline rod (22) side and the monocrystalline body (30) side of the shaper. The shaper (40) has an edge (42) that defines the boundary of the cross-section of the monocrystalline body (30) that is formed as the molten material solidifies.

Abstract: An apparatus for melting metallic stock as a crucible in which the metallic stock is received and melted, the stock in the crucible having an axis along which the force of gravity varies, and an inductive heating system which generates an inductive heating field having an inductive power density which varies along the axis. The inductive heating field interacts with the metallic stock in the crucible so that the radiation energy generated by the inductive heating field counteracts the hydrostatic pressure of the melt in the crucible.

Abstract: The solid metal to be melted is placed on a support, within an induction coil which is adapted to provide a greater electromagnetic force towards the lower portion of the quantity of metal. When energy is provided to the coil, the metal melts from the top downward, but the concentration of electromagnetic force towards the bottom of the metal causes the liquid metal to retain a cylindrical shape. When most of the metal is melted, the liquid metal passes through an opening in the support. In a preferred embodiment, the coil is movable relative to the quantity of metal, and at the beginning of the melting process only the top portion of the quantity of metal is disposed within the coil. As the quantity of metal melts, the coil is moved downward. The method may also be used for removing impurities from the quantity of metal.

Abstract: The improved zone-melt recrystallization apparatus is comprised of a port system for providing a thermal barrier between the recrystallization chamber and the loader assembly. A bellows system is used to lift a plurality of pins that support a silicon wafer being recrystallized. Flexure supports are designed to constrain the motion of the pins within the desired direction of motion of the wafer.

Abstract: An apparatus and method for inductively melting a quantity of metal, without having to contain the metal in a crucible, is described. The solid metal to be melted is placed within a first induction coil excited by an alternating current and adapted to provide a greater electromagnetic force towards the lower portion of the quantity of metal. The solid metal rests on a support, having an opening therethrough, which also comprises means for keeping the support at a low temperature relative to the metal as it melts. When energy in the form of the alternating current is provided to the coil, the metal melts from the top downward, but the concentration of electro-magnetic force towards the bottom of the metal causes the liquid metal to retain a cylindrical shape. A non-varying electromagentic field is applied to the quantity of metal to minimize violent stirring of the molten portion of the quantity of metal caused by the time-varying field.

Abstract: An RF induction heating apparatus for manufacturing single-crystal semiconductors having large diameters using the floating-zone melting process is provided in which a single turn induction heating coil suitable for zone melting and another heating coil suitable for controlling single-crystal growth are concentrically or eccentrically positioned to surround an outer surface of a floating zone in a crystalline semiconductor rod. Either the upper or lower peripheral edge of the outer surface of the single-turn induction heating coil is surrounded by and coupled to a annular collar, while both ends of the collar are arranged opposite each other across a gap. At least one conductive sector plate is affixed to a coil lower surface opposite a region of the semiconductor to be heated, so that even if both ends of the coil are spaced apart from each other due to the presence of a supply tube or the like, any gap between the two ends is shielded by the conductive sector plate(s).

Abstract: A method of controlling a floating zone applied to a crystal manufacturing system based on the FZ method and designed to enable the diameter at the crystallization boundary and the axial length of the floating zone or other similar quantities to desired values, in which a floating zone (20) is imaged with an imaging device (30); geometric quantities of the floating zone is measured from the image thereby obtained; the electric power (P) supplied to an induction heating coil (12) and the speed (V.sub.p) at which a raw-material rod (16) is moved relative to the induction heating coil so that the geometric quantities become equal to desired values. The geometric values include one Z.sub.i of the axial length of the floating zone, the distance (L) between the induction heating coil and a crystallization boundary (24) and the diameter (D.sub.n) of a melt neck portion located on the side of the crystallization boundary at a predetermined distance from the induction heating coil, and one D.sub.i of the diameter (D.

Abstract: For floating zone drawing of semiconductor rods having diameters greater than 100 mm, at the beginning of the zone drawing process, in particular during melting on of the seed crystal to the semiconductor rod to be drawn, a high load change and impedance change occurs. The power from the high-frequency (HF) generator is no longer coupled thereto optimally. Heating up the feed line to the induction heating coil is the result. This heating is avoided by connecting the HF generator via a feed line to a tank circuit device. A variable tank circuit capacitor connected in parallel and to the series oscillator circuit coil feeding one side of a parallel circuit of a heating circuit capacitor and the induction heating coil. The variable oscillator circuit capacitor is adjusted as a function of the voltage drop across the induction heating coil.

Abstract: An apparatus for use in a crystal manufacturing system based on a floating zone method or Czochralski method, adapted to control a quantity relating to the diameter of a crystal rod at the crystallization boundary, and designed to reduce hunting in the control of the quantity relating to the crystal diameter so as to prevent disturbance in crystallization and reduce irregularities in the surface of the crystal rod even if there is a discrepancy between a predetermined pattern and the ideal pattern with respect to the quantity to be controlled.

Abstract: Apparatus for producing crystalline ribbons of a material from a "crucible-less" configuration of bodies of the material including possible deposition on a substrate. Means for capacitively coupling electromagnetic energy into a source body of material are provided to appropriately induce electrical current gradients in order to control and restrict the molten zone and supress net loss of the heat of fusion from the balance of the ribbon-like body. The melt zone is replenished from any direction with ribbon or a bulk source to sustain the shape and size of the growing ribbon-like body. The heat of crystallization is selectively removed by a heat sink from one end of the melt zone in a direction substantially perpendicular to the direction of pulling.

Abstract: In a method of controlling a floating zone of a semiconductor rod of the present invention shown in FIG. 1, the diameter D.sub.s at a crystallization boundary of a crystal and the axial length of the floating zone are indirectly controlled by controlling a diameter D.sub.m of a crystallizing-side melt shoulder portion and the diameter D.sub.n of a constricted melt portion, respectively. Since these diameters D.sub.m and D.sub.n are used for predicting D.sub.s and L to be obtained after a given time has passed, the response speed and stability of the control are improved as compared with the direct control of D.sub.s and L. An apparatus for controlling a floating zone of a semiconductor rod of the present invention performs the above-described method. In another method, the zone length is directly or indirectly controlled by regulating a relative moving speed of the melting-side semiconductor rod relative to the heater, and the diameter D.sub.

Abstract: This invention relates to a single-turn induction heating coil used for floating-zone melting process. According to this invention, both ends of a single-turn coil are crossed each other in a peripheral direction of the coil so as to form an overlap section, and a pair of power supply portions are arranged on an outer peripheral wall so as to allow this RF current flowing through the coil, thereby forming a uniform magnetic field of the coil, and realizing magnetic concentration on an object. As a result, the floating-zone melting process can be stabilized to increase the productivity and striation, microscopic resistance variations and other quality defects of semiconductor crystals manufactured by the heating coil can be prevented as well.

Abstract: When semiconductor rods during floating zone melting are doped with dopants having a very low distribution coefficient, the non-homogeneous temperature distribution causes a relatively strong non-homogeneous separation of the dopants (striation). The homogeneity can be improved through an after-heater (6) connected to the heating coil (4) and arranged on the side of the monocrystalline rod part (2), the heater being coaxial with the coil and connected parallel to it.

Abstract: The process involves producing a monocrystal from the ferroelectric compound, annealing the monocrystal and cooling the latter in a zero longitudinal temperature gradient. The apparatus comprises means for producing the monocrystal, and heating means for annealing the monocrystal in a zero temperature gradient, as well as for cooling the monocrystal in a zero longitudinal temperature gradient after annealing. The strain-free monocrystals may be used in the production of surface wave filters, modulators and optical amplifiers.

Abstract: An apparatus for growing a GaAs single crystal by relying on the floating zone technique in a cylinder charged with a GaAs polycrystal and a GaAs single seed crystal, comprising an As container communicating with the interior of the cylinder to supply an optimum vapor pressure of As into the cylinder under the condition that a continuous temperature variation is established between this As container and the GaAs crystals charged in the cylinder, whereby a GaAs single crystal having little deviation from stoichiometry and having a good crystal perfection is obtained.

Abstract: A high temperature induction furnace (10) for drawing lightguide fiber (52) from a silica preform (44) has an axially located tubular zirconium dioxide susceptor (34) therein. Prior to use, at least a portion of the inside surface of the susceptor (34) is coated with a vapor deposited silica "soot" (54). The silica soot (54) is then consolidated at an elevated temperature. Surprisingly, such a technique substantially eliminates migration of zirconium dioxide particles from the susceptor (34) to the preform (44) and/or the fiber (52) without deleteriously affecting the susceptor (34) and/or the operation of the furnace (10).

Abstract: A pancake induction heating coil for crucible-free zone melting of semiconductor crystal rods, includes a primary winding surrounding a semiconductor rod to be remelted in the form of a ring through which cooling liquid flows, a secondary winding surrounding the primary winding and having a side facing the semiconductor rod, and an energy concentrator lying in the plane of the primary winding and having a circular opening formed substantially in the center thereof for the semiconductor rod, the side of the secondary winding facing the semiconductor rod being electrically conductingly connected to the energy concentrator.

Abstract: A high frequency induction furnace (10) for reflowing a portion of a lightguide preform (44) in order to draw a fiber (52) therefrom. The furnace (10) has a centrally located tubular susceptor (34) therein having a thin coating of the preform material (e.g., silica) on at least a portion of the inside surface thereof. A cylinder (62) is positioned in concentric, spaced relation about the susceptor (34) and is surrounded by an insulating grain (36). A high frequency coil (38) is energized to couple its electromagnetic field to the susceptor (34) to heat and reflow a portion of the preform (44) in order to draw the fiber (52) therefrom. The thin coating prevents contaminating particulates from migrating from small cracks in the inside surface of the susceptor (34) onto the preform (44) while the cylinder (62) prevents small particulate emanating from the insulating grain (36) from being drawn through larger cracks in the susceptor and onto the preform and/or the fiber 52.