Abstract: The branching of fractures in shale formations surrounding a wellbore can be enhanced so that more rock surface is exposed in the formation and more hydrocarbon resources can be recovered using smaller quantities of fracturing fluids. The branching of the fractures can be enhanced by establishing a substantially static sub-threshold fluid pressure in a well in a geological formation, and generating a pressure pulse in the well such that the pressure pulse combined with the substantially static sub-threshold fluid pressure forms a plurality of fractures in the geological formation. An arc jet insertable into a passage in the geological formation and having an electric arc channel can be used to generate the pressure pulse.

Abstract: The branching of fractures in shale formations surrounding a wellbore can be enhanced so that more rock surface is exposed in the formation and more hydrocarbon resources can be recovered using smaller quantities of fracturing fluids. The branching of the fractures can be enhanced by establishing a substantially static sub-threshold fluid pressure in a well in a geological formation, and generating a pressure pulse in the well such that the pressure pulse combined with the substantially static sub-threshold fluid pressure forms a plurality of fractures in the geological formation. An arc jet insertable into a passage in the geological formation and having an electric arc channel can be used to generate the pressure pulse.

Abstract: A method is disclosed for forming from a fiber slurry a three-dimensional fiber truss. The forming method involves compressing a fiber slurry or a fiber pulp between a pair of rigid foraminous dies to rapidly drive out most of the carrier fluid. The fiber retained between the dies is compacted into a pre-form fiber truss. The pre-form fiber truss is subsequently dried and consolidated in a heated press to produce a finished fiber truss. In panel applications, the fiber truss can be used by itself, or combined with other fiber trusses, to form a light-weight structural core for sandwich panels. Sandwich panels have numerous uses in packaging, material handling, construction, and furniture industries. Specific products include bulk bins, heavy-duty boxes, shipping containers, wall panels, roof panels, cement forms, partitions, poster displays, reels, desks, caskets, shelves, tables, and doors.

Abstract: All of the current processes for making molded particleboard products require very long furnish dwell times within a heated press, due to the low heat transfer rates from the heated molds to the furnish being compressed. Furnish dwell times vary between approximately one minute to more than 10 minutes, depending upon the part thickness. Since profitability of a particleboard molding operation is closely related to product throughput, these long furnish dwell times within the heated press limit production rates and continue to be a major economic concern to the industry. The essence of the invention is a heretofore unsuggested use of radiowave energy to speed production of molded particleboard parts by preheating the furnish prior to the application of heat and pressure within the forming mold. Because radiowaves propagate readily throughout the volume of the furnish, rapid heating is obtainable even for a loose, uncompacted particulate furnish that has very poor thermal conductivity.

Abstract: A method and apparatus for applying microwaves to flowable materials within a centrifuge are disclosed. The simultaneous application of microwaves and centrifugation to flowable materials may be utilized to rapidly separate immiscible components from emulsions and dispersions. Microwaves are guided along a waveguide structure within the centrifuge. A meandering path for the waveguide is chosen through the interior of the centrifuge and through the flowable material being centrifuged. Gradual variation in the radial distance of the waveguide from the axis of the centrifuge produces a gradual filling of the cross-section of the waveguide along its length, forming a gentle microwave beach within the waveguide. Excellent microwave coupling and power deposition into the flowable material results. There is no need to contain the flowable material behind a dielectric barrier, normally placed between the incident microwaves and the flowable material, since confinement is provided by centrifugal forces.

Abstract: A molded structural-wood-fiber product is disclosed that is formed in three dimensions under conditions of heat and pressure. The molded product has the form of a single-piece wood-fiber web consisting of corrugations having indentations along the ridges of the corrugations on both sides of the web. Sheet facings may be applied to one or both sides of the fiber web to form a stiff, lightweight composite panel that has similar stiffness both along and across the corrugations. Several fiber webs or composite panels may be bonded together in stacked configurations to produce high-strength, light-weight panels, beams or platforms for heavy-duty applications. The unique structure of the three-dimensional fiber web permits straightforward high-speed manufacture using a rigid mold and one-dimensional pressing forces.

Abstract: Methods and apparatus for rapidly drying and compacting wet fiber mats are disclosed. Rapid drying is produced by heating the wet fiber mats with a combination of radiowave energy and conductive heating. As the fiber mats are heated, three-dimensional compacting forces are applied by pressing the fiber mats between a flat surface press and a porous support on which is mounted a resilient mold insert. At high radio frequencies in the microwave range, power is transmitted from a multimode cavity through the porous support and resilient mold insert to the fiber mat. At low radio frequencies, differential radio-frequency voltages are applied directly to metal press plates which contain and compact the fiber mat. Methods and apparatus can be adapted to conveyorized or multi-opening press operations. Objects suitable for use with the invention are most commonly characterized by having a flat face surface on one side and webs or other features which may extend normal or generally normal to the flat surface.

Abstract: An improved radio frequency coaxial transmission line vacuum feed-through provided based on the use of a half-wavelength annular dielectric pressure barrier disk, or multiple disks comprising an effective half wavelength structure to eliminate reflections from the barrier surfaces. Gas-tight seals are formed about the outer and inner diameter surfaces of the barrier disk using a sealing technique which generates radial forces sufficient to form seals by forcing the conductor walls against the surfaces of the barrier disks in a manner which does not deform the radii of the inner and outer conductors, thereby preventing enhancement of the electric field at the barrier faces which limits voltage and power handling capabilities of a feedthrough.

Abstract: A resonant double loop radio frequency (rf) antenna for radiating high-power rf energy into a magnetically confined plasma. An inductive element in the form of a large current strap, forming the radiating element, is connected between two variable capacitors to form a resonant circuit. A real input impedance results from tapping into the resonant circuit along the inductive element, generally near the midpoint thereof. The impedance can be matched to the source impedance by adjusting the separate capacitors for a given tap arrangement or by keeping the two capacitances fixed and adjustng the tap position. This results in a substantial reduction in the voltage and current in the transmission system to the antenna compared to unmatched antennas. Because the complete circuit loop consisting of the two capacitors and the inductive element is resonant, current flows in the same direction along the entire length of the radiating element and is approximately equal in each branch of the circuit.

Abstract: A resonant cavity waveguide coupler for ICRH of a magnetically confined plasma. The coupler consists of a series of inter-leaved metallic vanes disposed withn an enclosure analogous to a very wide, simple rectangular waveguide that has been "folded" several times. At the mouth of the coupler, a polarizing plate is provided which has coupling apertures aligned with selected folds of the waveguide through which rf waves are launched with magnetic fields of the waves aligned in parallel with the magnetic fields confining the plasma being heated to provide coupling to the fast magnetosonic wave within the plasma in the frequency usage of from about 50-200 mHz. A shorting plate terminates the back of the cavity at a distance approximately equal to one-half the guide wavelength from the mouth of the coupler to ensure that the electric field of the waves launched through the polarizing plate apertures are small while the magnetic field is near a maximum.

Abstract: A radio frequency coaxial vacuum feedthrough is provided which utilizes a cylindrical ceramic vacuum break formed of an alumina ceramic. The cylinder is coaxially disposed and brazed between tapered coaxial conductors to form a vacuum sealed connection between a pressurized upstream coaxial transmission line and a utilization device located within a vacuum container. The feedthrough provides 50 ohm matched impedance RF feedthrough up to about 500 MHz at power levels in the multimegawatt range.