Abstract: A radial piezoelectric motor comprises a housing, a motor shaft rotatably mounted in the housing and a plurality of piezoelectric actuators inside the housing radially disposed about the axis of the motor shaft. The motor also includes circuitry for applying a voltage to the piezoelectric actuators to expand the actuators repeatedly and in succession and apparatus responsive to the repeated and successive expanding of the actuators for rotating the motor shaft.

Abstract: A lightweight direct methanol fuel cell unit (20) comprising a fuel cell stack (24) enclosed within a housing (22). In one embodiment the fuel cell stack includes a plurality of polymer electrolyte membrane electrode assemblies (52) stacked alternatingly with a plurality of bipolar plates (48). Each bipolar plate includes a cathode flow field (78) defined by a porous cathode flow field structure (56) and an anode flow field (62) defined by an upper plate (58) and a lower plate (60) separated from one another by a plurality of spacers (64). The anode flow fields are manifolded with one another via manifold embossments (118, 120) that are hermetically sealed with one another with a gasket (126). The fuel cell stack and housing are shaped so as to form four manifold regions (36) in the spaces between the fuel cell stack and housing.

Abstract: The invention is a laser power limiter. The limiter incorporates a layer of plasma forming particulate material supported optically in front of a sensor. A focussing means is positioned optically forward of the particulate layer to concentrate incident threat radiation on the particulate layer. The position of the particulate layer relative to the focussing means is selected such that the focal area encompassed by concentrated incident radiation encompasses a sufficient number of particulates to insure protective plasma formation and to insure that damage level incident radiation will be concentrated to an energy level exceeding the plasma formation threshold of the particulate material. The particulate layer is supported on a rotating window such that new areas of the layer can be exposed to incident radiation after a damage radiation incident.

Abstract: A laser preionization electrode (15, 17) formed of a dielectric tube (16) of square cross-section enclosing an electrode (18) of circular cross-section, the electrode (18) being of a large diameter on the order of 6.35 millimeters. A pair of such electrodes (15, 17) are located on either side of a main electrode (11) in a laser with the result that longer length preionization electrodes may be constructed while eliminating alignment problems of the prior art.

Abstract: A directly heated catalyst 10 is comprised of an electrically conductive ceramic substrate 12 having a catalytic coating 14 applied to at least an outer surface thereof. In an illustrative embodiment of the invention the catalytic coating is a noble metal or non-noblemetal coating. In accordance with one embodiment of the invention a high surface area form of platinum (Platinum Black) is deposited upon a ceramic substrate, such as a substrate comprised of SiC or SnO.sub.2. The coating is brought to its activation temperature by resistively heating the substrate with an electrical current. A temperature sensing device (20, 40), such as a thermocouple or a thermostat, may be coupled to the catalyst structure for sensing the temperature of the catalyst to control the heater current supplied to the substrate. The catalyst is shown to be useful for CO.sub.2 gas lasers.