Plasma accelerating apparatus and plasma accelerating method

Patent metadata

Field	Value
Publication number	US-10436183-B2
Application number	US-201716066899-A
Country	US
Kind code	B2
Filing date	Jan 6, 2017
Priority date	Jan 8, 2016
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

A plasma accelerating apparatus includes: a cathode (11) configured to supply electrons to a plasma acceleration region; an anode (12); a power supply (13) configured to apply a voltage between the cathode and the anode; a supply port (14) arranged on an outer circumference side of the cathode to supply a propellant to the plasma acceleration region; and a first magnetic field generator (15) configured to generate a first axial direction magnetic field in the upstream side region of the plasma acceleration region to suppress electrons supplied from the cathode from heading for the anode. Thus, the plasma accelerating apparatus and the plasma accelerating method having high thrust efficiency is provided.

First claim

The invention claimed is:

1. A plasma accelerating apparatus comprising:
a cathode configured to emit electrons to a direction of a predetermined center axis to supply the electrons to an upstream side region of a plasma acceleration region;
an anode having a ring shape when viewing from the direction of the center axis and arranged around the center axis;
a power supply configured to apply a voltage between the cathode and the anode;
a supply port arranged on an outer circumference side of the cathode to supply a propellant before plasmatization or a propellant after plasmatization to the plasma acceleration region; and
a first magnetic field generator arranged in a second direction from the plasma acceleration region when a motion direction of the electrons emitted from the cathode is defined as a first direction and a direction opposite to the first direction is defined as the second direction, and configured to generate a first axial direction magnetic field in the upstream side region of the plasma acceleration region to suppress that the electrons supplied from the cathode from heading for the anode,
wherein the first axial direction magnetic field has an axial direction component which is a component parallel to the center axis and monotonously degreases as heading for the first direction from the second direction on the center axis in the upstream side region of the plasma acceleration region, and a radial direction component which is a component orthogonal to the center axis and monotonously increases as heading for the first direction from the second direction on the center axis in the upstream side region of the plasma acceleration region, and
wherein the first magnetic field generator is arranged in the second direction from the supply port.

2. The plasma accelerating apparatus according to claim 1 , wherein the first magnetic field generator is arranged in the second direction from an end of the plasma acceleration region in the second direction.

3. The plasma accelerating apparatus according to claim 1 , wherein the first magnetic field generator is arranged on the outer circumference side of the cathode, and
wherein the supply port is arranged on the outer circumference side of the first magnetic field generator.

4. The plasma accelerating apparatus according to claim 1 , wherein the supply port is arranged on the outer circumference side of the cathode, and
wherein the first magnetic field generator is arranged on the outer circumference side of the supply port.

5. The plasma accelerating apparatus according to claim 1 , further comprising:
an orientation changing mechanism configured to change an orientation of the first magnetic field generator.

6. The plasma accelerating apparatus according to claim 1 , further comprising:
a second magnetic field generator configured to generate a second axial direction magnetic field in the plasma acceleration region,
wherein a direction of the second axial direction magnetic field generated by the second magnetic field generator is different from the direction of the first axial direction magnetic field generated by the first magnetic field generator.

7. The plasma accelerating apparatus according to claim 1 , further comprising:
a first wall section in contact with the plasma acceleration region;
an electron emission port arranged in the first wall section to emit the electrons supplied from the cathode.

8. The plasma accelerating apparatus according to claim 7 , wherein the anode is arranged on the first wall section.

9. The plasma accelerating apparatus according to claim 1 , wherein the anode is arranged on the outer circumference side of the supply port.

10. The plasma accelerating apparatus according to claim 1 , further comprising:
a first wall section in contact with the plasma acceleration region,
wherein the anode has a ring shape, and
wherein a distance between the first wall section and a downstream side end surface of the anode is equal to or less than ⅓ of the inner diameter of the anode.

11. A plasma accelerating method comprising:
providing a plasma accelerating apparatus, wherein the plasma accelerating apparatus comprises:
a cathode configured to emit electrons to a direction of a predetermined center axis to supply electrons to a plasma acceleration region;
an anode having a ring shape when viewing from the direction of the center axis and arranged around the center axis; and
a magnetic field generator arranged in a second direction from the plasma acceleration region, when a first direction is defined as a direction of movement of the electrons emitted from the cathode, and the second direction is defined as a direction opposite to the first direction;

generating a fan-shaped magnetic field in the plasma acceleration region by using the magnetic field generator;
applying a voltage between the cathode and the anode;
carrying out a first supply of supplying the electrons supplied from the cathode into the fan-shaped magnetic field;
carrying out a second supply of supplying a propellant before plasmatization or a propellant after plasmatization into the plasma acceleration region for the first direction from a supply port;
accelerating ions in a plasma generated in the plasma acceleration region by using an electric field generated by the anode and the electrons in the fan-shaped magnetic field so as to be focused for the center axis; and
neutralizing the ions through collision of the ions and the electrons in the fan-shaped magnetic field,
wherein the fan-shaped magnetic field has an axial direction component which is a component parallel to the center axis and monotonously degreases as heading for the first direction from the second direction on the center axis in the upstream side region of the plasma acceleration region, and a radial direction component which is a component orthogonal to the center axis and monotonously increases as heading for the first direction from the second direction on the center axis in the upstream side region of the plasma acceleration region, and
wherein the magnetic field generator is arranged in the second direction from the supply port.

12. The plasma accelerating method according to claim 11 , further comprising:
generating a Hall current through interaction of a fan-shaped magnetic field and an electric field generated between the cathode and the anode; and
generating a plasma in the plasma acceleration region through collision of a propellant before plasmatization or a propellant after plasmatization supplied into the plasma acceleration region and the electrons of the Hall current.

Assignees

• Mitsubishi Heavy Ind Ltd
• Univ Nagoya Nat Univ Corp

Inventors

• Yamazaki Takuya
• Sasahara Matsutaka
• Iwasaki Tomoji
• Yasui Masaaki
• SASOH Akihiro
• Iwakawa Akira
• Ichihara Daisuke
• Mizutani Keisuke

Classifications

• H05H1/04

  using magnetic fields substantially generated by the discharge in the plasma · CPC title

• F03H1/0068

  with a central channel, e.g. end-Hall type · CPC title

• F03H1/0012

  Means for supplying the propellant · CPC title

• H05H1/54 Primary

  Plasma accelerators · CPC title

• F03H1/0062 Primary

  grid-less with an applied magnetic field · CPC title