We have developed an instrument to measure the momentum flux from an intense plasma stream for which the standard techniques used for low-pressure gases (<10 Torr) at room temperature are unsuitable. With a response time of < 50 ms, this device, a plasma momentum meter, can measure forces of 10 -5-103 N onto surfaces of different materials immersed in dense plasmas (n≳1012cm-3). Such forces are transmitted predominantly by ionic and neutral species, with 10's of eV's of kinetic energy, are accompanied by high heat fluxes, and are pulsed. The momentum flux onto a biasable target plate is transferred via a suspended quartz tube onto a sensitive force transducer, a capacitance-type pressure gauge. This protects the transducer from thermal damage, arcing, and sputtering. An absolute force calibration of the PMM to 1% accuracy has been made and is described. A flat carbon target has been used in measurements of the momentum flux of He, Ne, Ar, and Kr plasmas produced in a magnetized linear plasma device.
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