Abstract: 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.

Abstract: A method for non-invasively measuring the impedance of a plasma discharge. Parallel anode and cathode electrodes are connected to a DC voltage source that ignites and sustains a plasma between the anode and cathode. A network analyzer applies a frequency-swept AC signal superimposed onto the DC voltage applied to the electrodes. The voltage of the AC signal reflected by the plasma is measured by the network analyzer through one of the electrodes used to sustain the plasma and is used to find the complex impedance of the plasma as a function of the applied AC frequency. Since the electrode serves dual purposes, the insertion of an additional physical probe that could introduce perturbations or contaminate the discharge is not necessary.

Abstract: 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.

Abstract: An rf probe is placed within a plasma and an rf signal from a network analyzer for a given dc bias voltage Vp is applied The frequency applied by the network analyzer, ?, is less than the plasma frequency, ?pe, and therefore is not in the resonant absorption range (?=?pe) 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(Zac), 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(Zac) occurs where the applied bias voltage Vp equals the plasma potential ?p. The plasma potential ?p can be found by taking the first derivative of Re(Zac) with respect to Vp, ? ( Re ? ( Z a ? ? c ) ? V p , and finding the value of Vp at which ? ( Re ? ( Z a ? ? c ) ? V p = 0 within error tolerances.

Abstract: An rf probe is placed within a plasma and an rf signal from a network analyzer for a given dc bias voltage Vp is applied The frequency applied by the network analyzer, ?, is less than the plasma frequency, ?pe, and therefore is not in the resonant absorption range (?=?pe) 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(Zac), 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(Zac) occurs where the applied bias voltage Vp equals the plasma potential ?p. The plasma potential ?p can be found by taking the first derivative of Re(Zac) with respect to Vp, ? ( Re ? ( Z a ? ? c ) ? V p , and finding the value of Vp at which ? ( Re ? ( Z a ? ? c ) ? V p = 0 within error tolerances.

Abstract: 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.