US 6,448,721 B2 · Cylindrical geometry hall thruster

Abstract

An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.

Claims20

Dependent claims

A Hall thruster with substantially closed electron drift, with an electric potential field applied across a cylindrical ceramic channel, such that ions are accelerated and can flown axially across a magnetic field, wherein an electrons drift substantially in the azimuthal direction, comprising of:

an applied magnetic field that is substantially axial in the vicinity of the gas entrance and substantially radial in the vicinity of the thruster exit;
and
a distributor of propellant gas, such that said gas is ionized in said channel and then said ions are accelerated by said electric field;
and
an anode, near the point of entry of the propellant gas into the channel;
and
a cathode-neutralizer, located outside said channel, that both neutralizes said ion flow and establishes total accelerating voltage of said ions;
and
a magnetic circuit that produces said magnetic field.

6 more elements

A Hall thruster with substantially closed electron drift, with an electric potential field applied across a cylindrical ceramic channel, such that ions are accelerated and can flow axially across a magnetic field, wherein an electrons drift substantially in the azimuthal direction, comprising of:

an applied magnetic field that is substantially axial in the vicinity of the gas entrance and substantially radial in the vicinity of the thruster exit;
and
a magnetic circuit that produces said magnetic field;
and
a distributor of propellant gas, such that said gas is ionized in said channel and then said ions are accelerated by said electric field;
and
an anode, near the point of entry of the propellant gas into the channel;
and
a cathode-neutralizer, located outside said channel, that both neutralizes said ion flow and establishes total accelerating voltage of said ions;
and
a second magnetic field, applied at the channel wall so as to combine with the first magnetic field in such a manner as to produce a cusp in the total magnetic field, thereby to enhance further the magnitude of the radial component of the total magnetic field in the vicinity of the cusp, and thereby to decrease the axial component of the total magnetic field in the vicinity of the cusp.
a magnetic circuit that produces said second magnetic field.

9 more elements

A Hall thruster with substantially closed electron drift, with an electric potential field applied across a substantially cylindrical ceramic channel, such that ions are accelerated and can flow axially across a magnetic field, wherein an electrons drift substantially in the azimuthal direction, comprising of:

a distributor of propellant gas, such that said gas is ionized in said channel and then said ions are accelerated by said electric field;
and
such that said gas distributor is arranged off the axis of symmetry of the thruster so as to optimize the ionization of the gas off the axis of symmetry;
and
an anode, near the point of entry of the propellant gas into the channel;
and
a magnetic pole placed in front of said anode on a ceramic piece arranged so as to create a short annular region in the vicinity of the gas entrance into the thruster;
and
such that said applied magnetic field is substantially radial in the vicinity of the gas entrance in said short annular region;
and
such that said applied magnetic field is substantially axial near the thruster axis in the vicinity of the magnetic pole in the cylindrical region of the thruster;
and substantially radial in the vicinity of the thruster exit;
and
a magnetic circuit that produces said magnetic field;
and
a cathode-neutralizer, located outside said channel, that both neutralizes said ion flow and establishes total accelerating voltage of said ions;
and
a second magnetic field, applied at the channel wall so as to combine with the first magnetic field in such a manner as to produce a cusp in the total magnetic field, thereby to enhance further the magnitude of the radial component of the total magnetic field in the vicinity of the cusp, and thereby to decrease the axial component of the total magnetic field in the vicinity of the cusp.
a magnetic circuit that produces said second magnetic field.

16 more elements

Dependencies are inferred from the claim text.

Cylindrical geometry hall thruster

Life of this patent

Cylindrical geometry hall thruster

Life of this patent

Abstract

Claims20