USA As Represented by Secretary of the Navy

William E Amatucci

Richard F Fernsler

Scott G Walton

Robert A Meger

David D Blackwell

David N Walker

Christopher D Cothran

George Gatling

Erik Tejero

Abhijit Sen

Christopher Crabtree

A detector for detecting optically undetectable sub-cm orbital debris. A ring detector comprising a current pulse transformer (CPT) in which a conducting wire coil is wrapped around a loop of high permeability material having a magnetic nanoparticle (MNP) core. Debris objects in low earth orbit become charged as they pass through local plasma. As each charged debris object passes through the coil-wrapped loop, its current generates an induced voltage pulse, which can be used to detect the presence of the debris object. By fielding such a detector on a satellite, a long duration survey of the debris distribution in the LEO region can be made as the satellite's altitude is systematically varied.

Orbital debris detection system using current pulse transformer

A method for non-invasively imaging plasma parameters has been invented. Crossed dipole pairs are used to differentiate changes in the measured complex self- and mutual impedances due to plasma density and magnetic field. Measurements of the complex self-impedance and mutual impedance between pairs of antennas over a wide range of frequencies provide spatial information to create an image of the plasma density and magnetic field. The spectral information is acquired simultaneously using a Gaussian monopulse as the driver signal.

Plasma impedance tomography for plasma parameter imaging

An apparatus and method for controlling electron flow within a plasma to produce a controlled electron beam is provided. A plasma is formed between a cathode and an acceleration anode. A control anode is connected to the plasma and to the acceleration anode via a switch. If the switch is open, the ions from the plasma flow to the cathode and plasma electrons flow to the acceleration anode. With the acceleration anode suitably transparent and negatively biased with a DC high voltage source, the electrons flowing from the plasma are accelerated to form an electron beam. If the switch is closed, the ions still flow to the cathode but the electrons flow to the control anode rather than the acceleration anode. Consequently, the electron beam is turned off, but the plasma is unaffected. By controlling the opening and closing of the switch, a controlled pulsed electron beam can be generated.

Apparatus and method for regulating the output of a plasma electron beam source

An rf probe is placed within a plasma and an rf signal from a network analyzer for a given dc bias voltage Vis applied The frequency applied by the network analyzer, &#x3c9;, is less than the plasma frequency, &#x3c9;, and therefore is not in the resonant absorption range (&#x3c9;=&#x3c9;) used to determine electron density in typical rf impedance probe operation. Bias voltages at the applied frequency are applied to the probe in a series of voltage steps in a range which includes the plasma potential. At each bias step, a value of Re(Z), the real part of the plasma's complex impedance, is returned by the analyzer. A local minimum in the real part of the impedance Re(Z) occurs where the applied bias voltage Vequals the plasma potential &#x3c6;. The plasma potential &#x3c6;can be found by taking the first derivative of Re(Z) with respect to Vp, and finding the value of Vp at which within error tolerances.

RF probe technique for determining plasma potential

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Fairfax Station, VA, United States of America

William E Amatucci