Leland Stanford Junior University

Space Systems/loral, LLC

Mark A Cappelli

Ronald W King

Gregory Rieker

Nicolas Claude Gascon

William A Hargus, Jr

Nathan B Meezan

Flavio Poehlmann-Martins

Michael H Loh

A spacecraft propulsion system has at least one chemical thruster, at least one electric thruster, a propellant supply arrangement that stores a propellant and a propellant conditioning arrangement configured to convert propellant into chemical species in a thermodynamic phase that can be readily ionized. The propellant is commonly supplied from the propellant storage device to each of the chemical thruster and the electric thruster. The chemical thruster has a gas generator and a high thrust accelerator; the electric thruster has a plasma generator and a high specific impulse accelerator. The propellant supply arrangement is configured to control flow of the propellant from the propellant supply arrangement to the gas generator and the propellant conditioning arrangement, and a first flow path connects propellant supply arrangement with the gas generator, and a second flow path connects propellant supply arrangement with the plasma generator.

Unified chemical electric propulsion system

Accelerated charged particles are provided by inductive amplification of particle energy in connection with a deflagration-mode plasma discharge. The deflagration mode discharge tends to increase particle energy relative to other operating modes. Inductive amplification of particle energy further increases output particle velocity. Inductive amplification can occur by formation of a current loop in the plasma discharge, and/or by a sudden increase in inductance due to collapse of the current distribution of the plasma discharge. Applications include particle therapy and production of radio-isotopes.

Method and apparatus for inductive amplification of ion beam energy

The operating characteristics of a linear geometry Hall plasma source scaled to operate in the 50 to 100 Watt power range are described. Two thruster acceleration channels are implemented-one of alumina and one of boron nitride. Differences in operation with the two channel materials are attributable to differences in the secondary electron emission properties. In either case, however, operation is achieved despite the lack of a closed electron current drift in the Hall direction, suggesting that there is an anomalous axial electron mobility, due to either plasma fluctuations or collisions with the channel wall. Strong low frequency oscillations in the discharge current, associated with the depletion of propellant within the discharge, are seen to appear and vary with changes in the applied magnetic field strength. The frequency of this oscillatory mode is higher than that seen in larger (and higher power) discharges, due to the decreased residence time of the propellant within the channel. Linear geometry Hall thrusters permit simpler magnetic circuit configurations and enable stacking of multiple thrusters to provide modular arrays.

Low power, linear geometry hall plasma source with an open electron drift

A process and apparatus for the synthesis of diamond from carbon precursors in supercritical water is described. The method involves the oxidation and/or pyrolysis of gaseous, liquid or solid phase carbon precursors in supercritical water (described by a critical pressure and critical temperature of at least 218 atm and at least 374.degree. C. respectively. The oxidation and/or pyrolysis products approach equilibrium concentrations in a reactor maintained at supercritical conditions for the mixture of supercritical water (solvent) and added reactants (solute). Besides carbon containing reactant precursors, additional reactants such as oxygen or hydrogen serve to enhance the oxidation/pyrolysis process. The reaction products undergo retrograde condensation resulting from imposed temperature gradients. The condensate is solid carbon, in the chemical form of carbon that is sp.sup.3 bond coordinated and of cubic or wurzite symmetry. The condensation process is enhanced by the presence of a seed diamond crystal.

Apparatus and method for synthesizing diamond in supercritical water

A supersonic, direct-current arcjet is designed for expansion into low pressure, the arcjet operates as mixtures of hydrogen and argon to convert molecular hydrogen to atomic hydrogen and direct the atomic hydrogen to a substrate surface. A hydrocarbon (methane or acetylene) is introduced in the arcjet plume where it is converted to hydrocarbon precursors and is directed to the substrate surface where it combines with the atomic hydrogen to produce a diamond film.

Growing community of inventors

Mountain View, CA, United States of America

Mark A Cappelli