The closed electron drift plasma accelerator comprises an annular ionization chamber, an acceleration chamber on the same axis as the ionization chamber, an annular anode, a hollow cathode, a first DC voltage source, an annular gas manifold, a magnetic circuit, and magnetic field generators. A coaxial annular coil is placed in the cavity of the ionization chamber, is provided with bias conductive cladding connected, together with the electrically-conductive material of the inside faces of the walls of the ionization chamber, to the positive pole of a second voltage source whose negative pole is connected to the anode, and constitutes an additional magnetic field generator which, together with the other magnetic field generators, forms a magnetic field having a magnetic line of force with an “X” point corresponding to a magnetic field zero situated between the coaxial annular coil and the anode.

Plasma accelerator with closed electron drift

An ion source (406), often used for materials processing applications in a vacuum processing chamber (410), is provided with an adaptive control system (426). The adaptive control system (426) has a microprocessor (425) and memory (427) that regulate the inputs of power (402) and gas flow (416) into the ion source (406). The adaptive control system (426) monitors and stores the dynamic input impedance properties and status of input devices (402, 407, 416) to the ion source (406). The adaptive control system (426) may additionally control magnetic fields (407) within the ion source (406). The adaptive control system (426) provides a multivariable control for driving any combination of input power (402), gas flow (416), magnetic field (407), or electrostatic ion beam extraction or acceleration field into the ion source (406).

Adaptive controller for ion source

The invention relates to a Hall effect plasma thruster including a main annular ionization and acceleration channel (120) having an open downstream end (129), at least one cathode, an annular anode that is concentric with the main annular channel (120), a pipe and a dispenser for feeding an ionizable gas into the channel (120), and a magnetic circuit for generating a magnetic field in the main annular channel (120). The main annular channel (120) includes portions of inner (127) and outer (128) annular walls located in the vicinity of the open end and (129) each including an assembly of conductive or semiconducting rings (150) juxtaposed in the form of blades separated by thin layers of insulation (152).

Hall effect plasma thruster

Plasma beam apparatus and method for the purpose of vacuum processing temperature sensitive materials at high discharge power and high processing rates. A gridless, closed or non-closed Hall-Current ion source is described which features a unique fluid-cooled anode with a shadowed gap through which ion source feed gases are introduced while depositing feed gases are injected into the plasma beam. The shadowed gap provides a well maintained, electrically active area at the anode surface which stays relatively free of non-conductive deposits. The anode discharge region is insulatively sealed to prevent discharges from migrating into the interior of the ion source. Thin vacuum gaps are also used between anode and non-anode components in order to preserve electrical isolation of the anode when depositing conductive coatings. The magnetic field of the Hall-Current ion source is produced by an electromagnet driven either by the discharge current or a periodically alternating current.

Gridless ion source for the vacuum processing of materials

A gas ionizable to produce a plasma is introduced into a channel within an ion source and into a hollow cathode embedded within the same ion source. A combined anode and manifold is located at a closed end of the channel and gas is introduced into the channel through the combined anode and manifold and into the hollow cathode. A heater and keeper electrode power supply is used to establish a hollow cathode and keeper electrode plasma. A discharge power supply is used to flow electrons from the hollow cathode in a predominately 180° direction to bombard the channel gas distribution and create a channel discharge plasma. A magnetic field generated by a permanent magnet circuit is concentrated by pole pieces at the open end of the channel in an orientation predominately transverse to the channel axis. Energetic electrons from the hollow cathode interact with the concentrated field to simultaneously ionize the channel gas and accelerates these ions through the open channel to form an ion beam. Simultaneously, electrons from the hollow cathode are emitted in a predominately axial direction to space-charge neutralize the ion beam.

Channel ion source

A PLASMA ACCELERATOR OF SHORT LENGTH WITH CLOSED ELECTRON DRIFT The means (31 to 33, 34 to 38) for generating a magnetic field in the main channel of the plasma accelerator are adapted to produce, in the main channel (24) an essentially radial magnetic field at the downstream end (225) of the channel (24), its induction being maximum at this point. The magnetic field has a minimum induction in the transition area in the vicinity of the anode (25), the absolute induction value of the field increasing again upstream of the anode (25), in the region of the buffer chamber (23) in order to produce a magnetic mirror effect. The magnetic field lines include, between the anode (25) and the downstream end (225) of the channel (24), a concavity oriented downstream, causing focusing of ions, the maximum ionisation density area being located downstream of the anode (25). The magnetic field generating means comprise several distinct magnetic field generating means (31 to 33) and inner (35) and outer (34) radial, plane pole pieces (34, 35) disposed at the outlet face on either side of the main channel (24) and linked to one another by a central core (38), a yoke (36) and a peripheral magnetic circuit (37) axially disposed outside of the main channel (24). The yoke (36) consists of radial elements located in the immediate vicinity of the anode (25) and passing through the annular buffer chamber (23), thereby creating spaces (13) for communication between the annular buffer chamber (23) and the main channel (24).

A plasma accelerator of short length with closed electron drift

Le moteur a plasma comprend un canal annulaire principal d'ionisation et d'acceleration (24) delimite par des pieces (22) en materiau isolant et ouvert a son extremite aval (225), au moins une cathode creuse (40) associee a des moyens (41) d'alimentation en gaz ionisable, et une anode annulaire (25) concentrique au canal annulaire principal (24) et disposee a distance de l'extremite aval ouverte (225). Une chambre tampon annulaire (23) qui presente dans le sens radial une dimension plus grande que celle du canal annulaire principal (24) s'etend en amont de celui-ci au-dela de la zone dans laquelle est placee l'anode annulaire (25). Des moyens (26) d'alimentation en gaz ionisable debouchent en amont de l'anode (25) a travers un distributeur annulaire (27) dans une zone distincte de la zone portant l'anode (25). Des moyens (31 a 33, 34 a 38) de creation d'un champ magnetique dans le canal principal (24) sont adaptes pour produire dans ce canal principal (24) un champ magnetique essentiellement radial qui presente un gradient avec une induction maximale a l'extremite aval (225) du canal (24).

Moteur a plasma a derive fermee d'electrons

A device for measuring variations in the thrust of a plasma accelerator with closed electron drift comprising a main annular channel for ionization and acceleration, at least one hollow cathode disposed outside the main channel and downstream therefrom, an anode, ionizable gas feed means associated respectively with the hollow cathode and with the anode, and magnetic field creation means. The device comprises a plurality of magnetic flux sensors (101 to 104; 31 to 33) disposed around the acceleration channel (24), a plurality of amplifiers (111 to 114) whose inputs receive the respective signals delivered by the magnetic flux sensors (101 to 104; 31 to 33) and a summing circuit (115) whose inputs are connected to the outputs of said amplifiers (111 to 114).

Device for measuring variations in the thrust of a plasma acceleration with closed electron drift

The plasma motor comprises a primary ionization and acceleration annular canal (24) delimited by parts (22) made of insulating material and open at its downstream end (225), at least one hollow cathode (40) associated with means (41) for supplying gas capable of being ionized, and an annular anode (25) concentric with said main annular canal (24) and placed at a distance from the open downstream end (225). An annular buffer chamber (24) which has, radially, a larger size than that of the main annular canal (24) extends upstream of the latter beyond the area in which is placed the annular anode (25). Means (26) for supplying gas capable of being ionized open upstream of the anode (25) through an annular distributor (27) into an area separated from the area carrying the anode (25). Means (31 to 33, 34 to 38) for creating a magnetic field in the main canal (24) are adapted to produce in said main canal (24) an essentially radial magnetic field having a gradient with maximum induction at the downstream end (225) of said canal (24).

Fixed plasma motor

The means (31 to 33, 34 to 38) for generating a magnetic field in the main channel of the plasma engine are adapted to produce, in said main channel (24) an essentially radial magnetic field at the downstream end (225) of the channel (24), its induction being maximum at this point. The magnetic field has a minimum induction in the transition area in the vicinity of the anode (25), the absolute induction value of the field increasing again upstream of the anode (25), in the region of the buffer chamber (23) in order to produce a magnetic mirror effect. The magnetic field lines include, between the anode (25) and the downstream end (225) of the channel (24), a concavity oriented downstream, causing focusing of ions, the maximum ionisation density area being located downstream of the anode (25). The magnetic field generating means comprise several distinct magnetic field generating means (31 to 33) and inner (35) and outer (34) radial, plane pole pieces (34, 35) disposed at the outlet face on either side of the main channel (24) and linked to one another by a central core (38), a frame (36) and a peripheral magnetic circuit (37) axially disposed outside of the main channel (24). The frame (36) consists of radial elements located in the immediate vicinity of the anode (25) and passing through the annular buffer chamber (23), thereby creating spaces (13) for communication between the annular buffer chamber (23) and the main channel (24).

Dominique Valentian

Papers

A plasma accelerator of short length with closed electron drift

Moteur a plasma a derive fermee d'electrons

Device for measuring variations in the thrust of a plasma acceleration with closed electron drift

Fixed plasma motor

Reduced length plasma engine with closed electron deviation.