Abstract: A thermionic converter having an emitter, a collector, and a source of cesium vapor is provided wherein the source of cesium vapor is differentially heated so that said source has a hotter end and a cooler end, with cesium vapor evaporating from said hotter end into the space between the emitter and the collector and with cesium vapor condensing at said cooler end. The condensed cesium vapor migrates through a porous element from the cooler end to the hotter end.

Abstract: A Vacuum Diode is constructed in which the electrodes of the Vacuum Diode are coated with a thin film of diamond-like carbonaceous material. The cathode and anode are separated by spacers and a rinse-able material, the rinse-able material which is later removed. Carbonaceous films and the related process for producing a thin film of ablated diamond are not previously known in connection with Vacuum Thermionic Converters, and provide a practical and improved means of constructing such devices.A Vacuum Thermionic Converter is optimized for the most efficient generation of electricity by utilizing a cathode and anode of very low work function. The relationship of the work functions of cathode and anode are shown to be optimized when the cathode work function is the minimum value required to maintain current density saturation at the desired temperature, while the anode's work function is as low as possible, and in any case lower than the cathode's work function.

Abstract: A stovepipe thermoelectric generator. The unit fits in a stovepipe of a coal or wood stove. At least one thermoelectric module is sandwiched between a hot side fin unit with fins extending into the flow of exhaust gases and a cold side fin unit with fins cooled by forced room air. A damper controls exhaust gas flow through a heat chamber, directing the exhaust gas through a generating side and a bypass side depending on a temperature indication. This prevents heat damage to the thermoelectric module. At least one fan is provided to force room air through cooling fins of the cold side fin unit An electric circuit is described for providing power for the fan and providing additional electric power for purposes such as charging a battery.

Abstract: A multiple cell thermionic converter having a generally tubular member of electrically conductive refractory metal with an internal cavity and a tubular envelope of electrically conductive refractory metal disposed in surrounding relationship to such generally tubular member. Electrically insulating ceramic material is disposed upon sections of facing surfaces of the envelope and tubular member, which is in the form of a body that has a central zone of plasma-sprayed refractory metal oxide selected from the group consisting of scandia, hafnia, zirconia and alumina, and a pair of flanking outer zones made of mixtures of the refractory oxide and particulate refractory metal. Refractory metal electron emitters and collectors are supported upon the ceramic bodies and juxtaposed in pairs with an annular gap therebetween to form a plurality of thermionic cells.

Abstract: A MEMS actuator is provided that produces significant forces and displacements while consuming a reasonable amount of power. The MEMS actuator includes a microelectronic substrate, spaced apart supports on the substrate and a metallic arched beam extending between the spaced apart supports. The MEMS actuator also includes a heater for heating the arched beam to cause further arching of the beam. In order to effectively transfer heat from the heater to the metallic arched beam, the metallic arched beam extends over and is spaced, albeit slightly, from the heater. As such, the MEMS actuator effectively converts the heat generated by the heater into mechanical motion of the metallic arched beam. A family of other MEMS devices, such as relays, switching arrays and valves, are also provided that include one or more MEMS actuators in order to take advantage of its efficient operating characteristics. In addition, a method of fabricating a MEMS actuator is further provided.

Abstract: A thermoelectric module with a plurality of electricity generating units each having a first end and a second end, the units being arranged first end to second end along an in-line axis. Each unit includes first and second elements each made of a thermoelectric material, an electrically conductive hot member arranged to heat one side of the first element, and an electrically conductive cold member arranged to cool another side of the first element and to cool one side of the second element. The hot member, the first element, the cold member and the second element are supported in a fixture, are electrically connected respectively to provide an electricity generating unit, and are arranged respectively in positions along the in-line axis. The individual components of each generating unit and the respective generating units are clamped in their in-line positions by a loading bolt at one end of the fixture and a stop wall at the other end of the fixture.

Abstract: An improved thermionic generator constructed using microenginerring techniques is described. This device is easy to construct in large numbers, efficient, and inexpensive. A preferred embodiment uses micromachined silicon to produce a thermionic converter cell. These may be joined together in large arrays to form a thermionic generator.

Abstract: An electronic timepiece comprises a casing formed of a thermally conductive material and having a first outer case portion and a second outer case portion connected together to define a space therebetween. The first outer case portion is exposed to the atmosphere and has a first temperature, and the second outer case portion is disposed in physical contact with the wrist of a user during use of the electronic timepiece and has a second temperature different from the first temperature. A thermoelectric element is disposed in the space of the casing for generating an electromotive force due to heat transfer between the first and second outer case portions resulting from the difference between the first and second temperatures. The thermoelectric element has a first support member at one end thereof connected to the first outer case portion of the casing and a second support member at a second end opposite the first end and connected to the second outer case portion of the casing.

Abstract: An indexing apparatus is disclosed that can be used to rotate a gear or move a rack in a precise, controllable manner. The indexing apparatus, based on a reciprocating shuttle driven by one or more actuators, can be formed either as a micromachine, or as a millimachine. The reciprocating shuttle of the indexing apparatus can be driven by a thermal, electrostatic or electromagnetic actuator, with one or more wedge-shaped drive teeth of the shuttle being moveable to engage and slide against indexing teeth on the gear or rack, thereby moving the gear or rack. The indexing apparatus can be formed by either surface micromachining processes or LIGA processes, depending on the size of the apparatus that is to be formed.

Abstract: Machine structures each comprising a stack of a plurality of micromachine layers laminated together are presented, along with fabrication methods therefore. Each machine structure includes a movable member(s) defined from microstructure of at least one layer of the plurality of micromachine layers comprising the stack. During fabrication, the micromachine layers are separately formed using VLSI techniques and then subsequently laminated together in a selected arrangement in the stack to define the machine structure.

Abstract: A device that utilizes the difference in NEAF values between two plates to generate voltage is disclosed. The difference in NEAF values is created by shaping or varying the thickness of two plates to create a voltage differential which is available to drive electrical devices.

Abstract: A device that allows limited flow of free electrons between the plates of a converter is disclosed. The converter converts constant temperature ambient heat into electrical energy which is available to drive electrical devices.

Abstract: An improved thermionic electric converter uses a wire grid cathode to provide a larger surface area for electrons to boil off. Alternately or additionally, the larger electron emission surface area can be achieved by using a curved electron emission surface. A laser provides quantum interference to electrons just before they reach the anode, thereby lowering their energy levels such that they more readily are captured by the anode. The arrangement provides improved conversion efficiency and reduced electron scatter.

Abstract: Methods and apparatus for detecting the presence of explosives by analyzing a vapor sample from the suspect vicinity utilize at least one microcantilever. Explosive gas molecules which have been adsorbed onto the microcantilever are subsequently heated to cause combustion. Heat, along with momentum transfer from combustion, causes bending and a transient resonance response of the microcantilever which may be detected by a laser diode which is focused on the microcantilever and a photodetector which detects deflection of the reflected laser beam caused by heat-induced deflection and resonance response of the microcantilever.

Abstract: Microelectromechanical actuators include at least one arched beam which extends between spaced apart supports on a microelectronic substrate. The arched beams are arched in a predetermined direction and expand upon application of heat thereto. A coupler mechanically couples the plurality of arched beams between the spaced apart supports. Heat is applied to at least one of the arched beams to cause further arching as a result of thermal expansion thereof, and thereby cause displacement of the coupler along the predetermined direction. Internal heating of the arched beams by passing current through the arched beams may be used. External heating sources may also be used. The coupler may be attached to a capacitor plate to provide capacitive sensors such as flow sensors. The coupler may also be attached to a valve plate to provide microvalves. Compensating arched beams may be used to provide ambient temperature insensitivity.

Abstract: A thermo-sensitive actuator capable of operating without the need of providing a temperature detector as a separate member. The actuator includes a stator made of a magnetic material to form a yoke. A rotor is rotatably provided in an opening provided in the stator. The actuator further includes pole pieces for magnetically connecting the stator and the rotor. A magnetic source is provided in any of the magnetic paths formed by the constituent elements. A thermo-sensitive magnetic material, which shows a change in magnetic characteristics, e.g. permeability, saturated magnetic flux density, or residual magnetic flux density, according to temperature, is provided in a part of the magnetic paths.

Abstract: An improved thermionic electric converter uses a wire grid cathode to provide a larger surface area for electrons to boil off. Alternately or additionally, the larger electron emission surface area can be achieved by using a curved electron emission surface. A laser provides quantum interference to electrons just before they reach the anode, thereby lowering their energy levels such that they more readily are captured by the anode. The arrangement provides improved conversion efficiency and reduced electron scatter.

Abstract: A resonant thermoelectric generator includes a thermoelectric power converter connected in series with a resonant circuit. A current generated by the thermoelectric power converter is cycled back and forth in the resonant circuit. The polarity of the thermoelectric power converter with respect to the resonant circuit is switched back and forth to correspond with the direction of the current. In a second embodiment, the thermoelectric power converter is coupled to the resonant circuit through a transformer, and its polarity is also switched to correspond with the direction of the current. In both embodiments, a negative retarding voltage that builds up in the thermoelectric power converter is eliminated by switching its polarity to always correspond with the direction of the current, so that energy is added to the resonant circuit in each cycle, and power is very efficiently converted from heat directly into electricity.

Abstract: An actuation system for the control of multiple shape memory alloy elements is achieved by arranging the shape memory actuators into a matrix comprised of rows and columns which results in approximate a fifty percent reduction in the number of electrical connecting wires. This method of actuation provides the scope for resistance measurements of the shape memory alloy actuators and therefore feedback control of the actuators can be accomplished without additional wires.

Abstract: A nonelectromagnetic motor comprising a base, a bent shaft which is rotable relative to the base wherein the bent shaft comprises a straight portion aligned with a main axis and an offset portion that is offset with respect to the main axis; and a drive means for driving the offset portion of the bent shaft along a generally circular path in a plane perpendicular to the main axis to rotate the bent shaft. The bent shaft and drive means for driving the bent shaft can be selected from piezoelectric, magnetostrictive, rheological and shape memory alloys. The drive means of the nonelectromagnetic motor can additionally comprise a shell which shell surrounds and houses the bent shaft and precesses or gyrates which in turn causes the bent drive shaft to rotate. The nonelectromagnetic motor does not rely on friction for the application of torque upon a rotor.

Abstract: A thermo-sensitive actuator capable of operating without the need of providing a temperature detector as a separate member. The actuator includes a stator made of a magnetic material to form a yoke. A rotor is rotatably provided in an opening provided in the stator. The actuator further includes pole pieces for magnetically connecting the stator and the rotor. A magnetic source is provided in any of the magnetic paths formed by the constituent elements. A thermo-sensitive magnetic material, which shows a change in magnetic characteristics, e.g. permeability, saturated magnetic flux density, or residual magnetic flux density, according to temperature, is provided in a part of the magnetic paths.

Abstract: Apparatus is disclosed in which a pair of elongated solid cylindrical metal conductors mounted with their central axes mutually parallel are connected at their ends to form a closed electrical circuit path, there being heat sinks at spaced positions along their length which serve as heat transfer means setting up a temperature gradient along the lengths of the conductors. A strong electrical current flow in the conductors creates a circumferential magnetic field in the metal directed at right angles to the heat flow and this, by the Nernst Effect, produces a radial electric field gradient in the metal coupled with the transient accumulation of stored electrical energy. The apparatus disclosed serves for the experimental testing of energy conversion and storage by thermoelectric processes occurring in the metal and the ultimate utilization of the technology involved.

Abstract: Magnetic heat engines directly converting heat to electricity, using emf induced by demagnetization. Generated power manifests as negative resistance, and almost any kind and shape of magnetic medium can be used. Electromagnetic engines are also tolerant to non-uniform heating, inherently non-contact and non-mechanical, easy to model and design, and operable at high frequencies. The engines are suitable for augmenting local heating, refrigeration without fluid refrigerants, efficient cooling of cryogenic components, synchronous cooling of digital circuits, completely solid-state power generation, and improvement of power plant efficiency and control.

Abstract: A thermoelectric module includes a switching circuit for switching the connection between a first thermoelectric element and a second thermoelectric element between series connection and parallel connection, a voltage detecting circuit for controlling the switching circuit by detecting the voltage of the second thermoelectric element, and a storage battery circuit for storing electricity utilizing the voltages generated by the first thermoelectric element and the second thermoelectric element connected by the switching circuit. A voltage generated from an applied temperature difference is detected by the voltage detecting circuit. If there is a sufficient temperature difference, the first thermoelectric element and second thermoelectric element are connected in parallel by the switching circuit to charge the electricity in the storage battery circuit using the doubled current.

Abstract: The present invention embodies a piezo-pyroelectric energy converter and is directed to a method and apparatus for conversion of thermal energy to electrical energy and refrigeration. The present invention utilizes one or more piezo-pyroelectric materials with thermally conductive metal electrodes, which resonate at a high frequency and are in thermal communication with hot and cold heat sinks to create a thermal gradient and heat flow along the metal electrodes and the piezo-pyroelectric material.

Abstract: A thermoelectric generator system including a refrigerator of the of the absorption type having no moving parts and operating with ammonia, water and hydrogen to extract heat from a heat source and discharge heat from an absorber and having at least one thermocouple positioned to intercept heat flow from the heat source to the boiler and/or from the condenser to the evaporator. The system is arranged such that a boiler from one system absorbs heat discharged from the absorber of one or more other identical systems so that systems can be ganged together to produce a combine system having increased efficiency.

Abstract: An electrical device functions as a thermally energized DC power source. The device has a base plate of conductive metal. A number of electrode points protrude upward from the base plate, terminating in a sharp edge. A collection plate of conductive metal is positioned above the sharp upper edges of the electrode points. The gap between the electrode points and between the collection plate and the electrode points is electrically insulated. An electrical potential exists between the base plate and the upper collection plate while the device is at and above room temperature. The potential difference increases as the temperature increases.

Abstract: A thermoelectric generator for producing electric power for a motor vehicle from the heat of the exhaust gasses produced by the engine of the motor vehicle. The exhaust gasses pass through a finned heat transfer support structure which has seat positions on its outside surface for the positioning of thermoelectric modules. A good contact cylinder provides a framework from which a spring force can be applied to the thermoelectric modules to hold them in good contact on their seats on the surface of the heat transfer support structure.

Abstract: In an electric power generating element, either positive or negative electrode includes a composition containing an organic compound as a main agent and the positive electrode has an electrically conductive substance so that relatively low-temperature thermal energy is efficiently converted to electric energy. Polyethylene glycol is employed as the organic compound and graphite or a graphite composition is employed as the conductive substance. Salt providing ionic conductivity may be added to the organic compound or polyethylene glycol, and the negative electrode may be formed of a metal having an ionization tendency as large as or larger than copper or a composition of the metal.

Abstract: Optical energy, generated by a laser or laser diode source, is coupled into an optical fiber having core dimensions typically ranging from 5 to 200 micrometers. Overall outside dimensions of such fibers range between 50 and 500 micrometers. With such fibers, optical energy can be transmitted with minimal losses over distances of several meters to several hundred meters. Power levels of 1 to 100 Watts can be transmitted without problems. With such power available a wide variety micro machines and other miniature devices can be operated by converting the optical energy into mechanical energy through thermodynamic or photoacoustical means. Preferably transmitted wavelengths will match an absorption peak of a thermodynamic work medium thereby providing efficient conversion from optical to mechanical energy. An alternative method uses an optomechanical conversion means to generate mechanical power at a remotely situated micro machine or micro actuator.

Abstract: The invention encompasses a torus formed by heated and cooled junctions of dissimilar metals such as copper and nickel to generate a low voltage current and form an electrical path of greatly enhanced conductivity wherein a greater current flow may be induced to form a stronger magnetic field. Current at higher voltage may be incrementally removed by magnetic field arrangements to act as magnetic variable switches while at the same time the magnetic field is contained and current also flows through the torus.

Abstract: Collector for thermionic energy converter of a new type with low electronic work function. A thermionic energy converter includes an emitter and a collector and a space provided therebetween to which is supplied vapor of a thermionic material, for example cesium or other alkali metal. The emitter is heated from an external heat source so that it emits electrons to the collector. The collector is at least partly covered by a thin layer of a material, for example carbon, which is capable of interacting with the thermionic material and form excited states of this and maintain a layer of excited thermionic material on the surface of the collector. The new collector for thermionic converters exhibits a very low work function, which implies diminished losses is the energy conversion.

Abstract: A thermoelectric conversion member formed by a thermoelectric conversion element has a split ring shaped transverse cross section. Electrodes are disposed on ring ends of the thermoelectric conversion member facing each other. A magnetic field generating unit generates a magnetic field in a direction perpendicular to the transverse cross-sectional plane of the thermoelectric conversion member. A heating unit for heating one side of an annular wall of the thermoelectric conversion member and a cooling unit provided on the opposite side of the annular wall of the thermoelectric conversion member produces a temperature gradient in a direction radially of the thermoelectric conversion member. Electric field is induced in the direction perpendicular to both directions of the magnetic field and the temperature gradient, that is in the circumferential direction of the ring of the thermoelectric conversion member under the Nernst effect, enabling an electric voltage to be taken out at the electrodes.

Abstract: A thermoelectric generator includes a plurality of thermoelectric junctions embedded in each of a pair of thermally conductive and electrically non-conductive layers, these layers being separated by a thermally and electrically non-conductive layer. The junctions are connected to form a thermopile. An absorbent layer is provided adjacent one of the thermally conductive layers. A liquid such as water is applied to the absorbent layer, so that evaporation of the liquid from the absorbent layer enhances the temperature differential between the two thermally conductive layers.

Abstract: A flat motor. The flat motor comprises a substrate, a cantilevered, resilient lever arm mounted, by a passive end, on the substrate; and a shape-memory transducer acting on the lever arm wherein movement of the transducer deflects the lever arm.

Abstract: A thermionic generator (10) has a heated metal heat tube (11) journaled through a set of star-shaped emitters (12) and a set of electrically insulative spacers (13). The generator also has a collector (23) positioned about the grouped emitters and spacers a selected distance from the emitters. A cooling jacket (33) is positioned about the collector for cooling the collector during operation. A pair of seals (29) electrically and hermetically seal the cooling jacket about the heat tube.

Abstract: In an electric timepiece using a small and thin thermoelectric element wherein a first insulator made of silicon is on the heat absorbing side and a second insulator made of silicon is on the heat radiating side, when a temperature difference is applied thereon such that the temperature on the heat absorbing side is higher than that on the heat radiating side, heat is transferred in a direction from the insulator 101 to the insulator. In that case, electrons move toward the insulator on the heat radiating side in a n-type semiconductor. Holes move toward the insulator on the heat radiating side in a p-type semiconductor. The n-type semiconductor and the p-type semiconductor are electrically connected in series via a connector and therefore, the heat transfer is converted into current and an electromotive force can be provided between output terminals. Further, the electromotive force is stored in an electric storage means.

Abstract: The apparatus is a combined Alkali Metal Thermal to Electric Converter (AMTEC) and a thermionic energy converter which are mated by the use of a common heat transfer device which can be a heat pipe, pumped fluid or a simple heat conduction path. By adjusting the heat output surface area of the thermionic converter and the heat input surface area of the AMTEC, the heat transfer device accomplishes not only the transfer of heat from the output of the thermionic converter to the input of the AMTEC, but also the transformation of the heat density to match the requirements of the AMTEC input. The electrical current through the combined devices is also matched by adjusting the heated surface area of the AMTEC.

Abstract: In an electric power generating element, either positive or negative electrode includes a composition containing an organic compound as a main agent and the positive electrode has an electrically conductive substance so that relatively low-temperature thermal energy is efficiently converted to electric energy. Polyethylene glycol is employed as the organic compound and graphite or a graphite composition is employed as the conductive substance. Salt providing ionic conductivity may be added to the organic compound or polyethylene glycol, and the negative electrode may be formed of a metal having an ionization tendency as large as or larger than copper or a composition of the metal.

Abstract: A collector element for a thermionic electric converter that reduces electron scatter and improves conversion efficiency is provided. The collector element includes an outer casing and a highly charged member surrounded by insulating layers that minimize loss of static charge on the highly charged member. The collector element additionally includes a conductive layer of copper sulfate gel impregnated with copper wool fibers. Copper sulfate gel minimizes electron scatter, while providing advantageous electrical properties. The copper wool fibers are in electrical contact with a plurality of ancillary buses which transmit electrical energy to a main bus that provides the electrical energy collected to an external circuit. The main bus is also in electrical contact with the conductive layer.

Abstract: A heater mechanism incorporating a thermoelectric converter for use with a self-powered, solid, liquid or gaseous fueled, heater. During operation of the heater mechanism the thermoelectric converter supplies sufficient electrical power to (a) sustain the heater in operation, (b) maintain the starter battery at full charge, and (c) provide auxiliary power to remove and transport heat to desired locations away from the heater. The converter is a highly compact design (high power output per unit volume of space) and lends itself to high volume (mass production) and automated assembly techniques to produce it inexpensively. The thermoelectric converter is made of fewer components than prior art devices. A number of components in the thermoelectric stack serve dual or even multi-functions. The thermoelectric stack components are bonded or mounted together in such a manner as to permit handling as a unit.

Abstract: This invention is for an object moving actuator composed of a stack of independently controllable layers which convert thermal exobaric pulses into mechanical motion. Each layer can be a lifter for moving the stack normal to the object to be moved or a tangenter for moving the stack tangentially to the object. Each layer has a plurality of chambers having a heat source and a thermal expansive material contained therein. The heat source is controlled by a controller to generate a heat pulse which expands the thermal expansive material thereby moving a rolling barrier to make the layer move normally or tangentially. Preferably two pair of actuator stacks work together to alternately engage and move the object. The first pair makes contact with the object by lifter motion and moves the object by tangenter motion while the second pair is lifted off the object and retraces to get into position to contact and translate the object.

Abstract: The entropic echinoid 2 applies force to an object 6 with the cummulative effect of myriad feet 8 activated by fluid expansion pulses from electrical resistance heaters 30. Each heater lying in a fluid filed socket 10 of a substrate 4 and activated by a signal from a corresponding foot position sensing capacitor 26. The entropic echinoid is useful in high temperature environments for motors, actuators, bearings and clutches.

Abstract: A micro electrostatic cooling fan arrangement is provided which includes a heat source having a planar surface, a stator attached to the heat source, an axle attached to the heat source and spaced from the stator, a rotary element including a hub having an aperture therein and a fan blade, the axle passing through the aperture of the hub and the fan blade having a major surface thereof disposed at an angle with respect to the surface of the heat source and attached to the hub at one end, with the other end of the fan blade being adjacent to but spaced from the stator and a voltage source applied to the stator having sufficient voltage to charge the fan blade.

Abstract: A process for the formation of a force field comprising cooling at least one crystal selected from potassium tartrate, cesium nitrate, rubidium nitrate, tartaric acid, cadmium nitrate and thorium nitrate to a temperature below about 110K. The force field comprises an electric field and a mass attraction field which maintains its intensity over long time periods. The crystal is encapsulated in, e.g., nonconductive epoxy.

Abstract: A process for the formation of a force field comprising cooling at least one crystal selected from potassium tartrate, cesium nitrate, rubidium nitrate, tartaric acid, cadmium nitrate and thorium nitrate to a temperature below about 110K. The force field comprises an electric field and a mass attraction field which maintains its intensity over long time periods. A method is also provided for establishing a force field at a location remote from the cooled crystal by means of an electrical connection to the cooled crystal by an insulated electrical conductor. The invention includes a device for forming the force field.

Abstract: A thermoelectric energy converter incorporates thermocouples in a circuit carrying A. C. current via capacitors which provide electrical coupling but obstruct heat transfer between hot and cold junctions. The cyclic current oscillations through the capacitors are diverted by special circuits so as to be rendered asymmetric as current oscillations through the thermoelectric junctions. One such circuit includes the use of a diode configuration regulating current flow through different thermoelectric junctions spaced apart in the thermal gradient. Another involves the action of a unidirectional magnetic field having a polarizing effect on a three-metal thermoelectric junction.

Abstract: A thermionic energy converter comprises an emitter, a transparent collector support generally parallel to an emitting surface of the emitter, a conductive film collector from about 10 to about 3,000 Angstroms in thickness covering a support surface of the collector support, and an enclosure for maintaining a controlled atmosphere in the gap between the conductive film collector and the emitting surface. According to another embodiment an improvement is set forth in a thermionic energy converter comprising an emitter, a collector and an enclosure adapted to maintain a controlled atmosphere in the emitter-collector gap. The improvement comprises an insulator post supportingly attaching the emitter and the collector. The embodiments are advantageously used together.

Abstract: A method and flux pump for inducing electrical energy from superconducting and ferromagnetic material comprising initially magnetizing said ferromagnetic material, and applying heat to raise the ferromagnetic material above its magnetic transition temperature, so as to cause a loss of magnetization and induce a current in a superconducting circuit.

Abstract: A support is provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.