US-12628263-B2 - Magnetic orbital angular momentum beam acceleration

US12628263B2US 12628263 B2US12628263 B2US 12628263B2US-12628263-B2

Abstract

A magnetic orbital angular momentum beam accelerator will accelerate charged particles, electrons or ions, from rest in zero or low magnetic field into a high magnetic field regions with high kinetic energies in the form of magnetic orbital angular momentum. For example, a beam injector that accelerates electrons or ions into 1T magnetic fields with tens of keV kinetic energies transverse to the magnetic fields can be used to heat magnetically confined plasmas, to inject an initial energetic plasma component with high magnetic orbital angular momentum and to produce highly transverse particle momenta to the magnetic field for electron or ion beam lithography.

Inventors

Christopher George Tully
Wonyong Chung

Assignees

THE TRUSTEES OF PRINCETON UNIVERSITY

Dates

Publication Date: 20260512
Application Date: 20220802

Claims (14)

1 . A method for particle acceleration, comprising: providing particles in a zero or low magnetic field; causing the particles to be in cyclotron motion in a magnetic field that is strong compared to a momentum of the particles, the particles having a gyroradius that is small compared to a transverse dimension of an injection aperture through which the particles will travel, wherein the magnetic field has a transverse gradient along an average path of the particles; and utilizing a complementary electric field to balance a gradient-B drift that is transverse to an average path of the particles and accelerate the particles under work of the transverse gradient.
2 . The method according to claim 1 , wherein the particles comprise electrons, ions, or a combination thereof.
3 . The method according to claim 1 , further comprising directing the particles towards a confined plasma.
4 . The method according to claim 1 , further comprising directing the particles towards a substrate.
5 . The method according to claim 4 , wherein the substrate is a semiconductor.
6 . A magnetic orbital angular momentum beam accelerator, comprising: a tapered dipole magnet winding configured to have a magnetic field positioned to allow particles to enter the tapered dipole magnet winding, the magnetic field being a low magnetic field configured to cause the particles to begin cyclotron motion, and has a magnetic field gradient that is a transverse gradient along an average path expected of the particles; and a field cage comprising a plurality of electrodes, configured to form a complementary electric field to balance a gradient-B drift that is transverse to an average path of a beam of the particles and accelerate the particles under work of the magnetic field gradient.
7 . The magnetic orbital angular momentum beam accelerator according to claim 6 , wherein the field cage is placed within a counter-dipole coil in an upper diagnostic port of a tokamak reactor.
8 . The magnetic orbital angular momentum beam accelerator according to claim 6 , wherein the field cage includes, or is placed within, coils of a solenoid, custom superconducting dipole coils, iron pole-face magnets with shaped pole-faces, configurations of permanent magnets, or a combination thereof.
9 . The magnetic orbital angular momentum beam accelerator according to claim 6 , further comprising an einzel lens configured to accelerate the particles from an initial magnetic field towards the tapered dipole magnet winding, the initial magnetic field being a zero or low magnetic field.
10 . The magnetic orbital angular momentum beam accelerator according to claim 9 , wherein the particles are reflected off a repelling electrode of the einzel lens into the tapered dipole magnet winding.
11 . The magnetic orbital angular momentum beam accelerator according to claim 6 , wherein the particles comprise at least one of electrons and ions.
12 . The magnetic orbital angular momentum beam accelerator according to claim 6 , wherein the particles are accelerated in a low vacuum.
13 . The magnetic orbital angular momentum beam accelerator according to claim 6 , wherein the tapered dipole magnet winding comprises superconducting magnets.
14 . The magnetic orbital angular momentum beam accelerator according to claim 6 , wherein the tapered dipole magnet winding is symmetrical around a plane extending through a central axis, each half of including a plurality of loops, each loop in the plurality of loops having a contoured rounded rectangular shape, each loop having one side that is substantially located at a first end, and where each loop has a different length.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority to U.S. Provisional Pat. App. No. 63/228,463, filed Aug. 2, 2021, and is incorporated by reference herein in its entirety. TECHNICAL FIELD The present disclosure is drawn to devices, systems, and methods for creating and using particle beams. BACKGROUND Current particle beam heating techniques for magnetically confined plasmas rely on neutral beam injectors to allow external, neutral particles to enter the magnetically confined region. Neutral particles have zero magnetic orbital angular momentum and when they interact in the plasma, a large fraction of these particles after ionization have low magnetic orbital angular momenta and are not strongly confined. Additionally, current particle beam lithography techniques use particles with large linear momentum to cut customized shapes on surfaces, such as nanostructured surfaces, but such techniques require a large linear momentum normal to the surface, which can negatively impact the structure of several layers below the surface layer. BRIEF SUMMARY To avoid these issues, a method and system for particle acceleration may be provided. In some embodiments, a method for particle acceleration may be provided. The method may include providing particles in a zero or low magnetic field (i.e., a magnetic field whose strength is sufficiently low to allow for ballistic motion out of the source). The method may include causing the particles to be in cyclotron motion in a magnetic field that is strong compared to a momentum of the particles. The particles may have a gyroradius that is small compared to a transverse dimension of an injection aperture through which the particles will travel, where the magnetic field has a transverse gradient along an average path of the particles. The method may include utilizing a complementary electric field to balance a gradient-B drift transverse to the average path of the particles and accelerate the particles under work of the transverse gradient. In some embodiments, the particles may include electrons, ions, or a combination thereof. In some embodiments, the method may include directing the particles towards a confined plasma. In some embodiments, the method may include directing the particles towards a substrate. In some embodiments, the substrate may be a semiconductor. In some embodiments, a magnetic orbital angular momentum beam accelerator may be provided, e.g., from a source (such as an electron gun). The accelerator may include a tapered dipole magnet winding configured to have a magnetic field positioned to allow particles to enter the tapered dipole magnet winding, the magnetic field being a low magnetic field configured to cause the particles to begin cyclotron motion. The tapered dipole magnet winding may have a magnetic field gradient that is a transverse gradient along an average path expected of the particles. The accelerator may include a field cage. The field cage may include a plurality of electrodes, configured to form a complementary electric field to balance a gradient-B drift transverse to the average path of a beam of the particles and accelerate the particles under work of the magnetic field gradient. In some embodiments, the field cage may be placed within a counter-dipole coil in an upper diagnostic port of a tokamak reactor. In some embodiments, the field cage may include, or be placed within, coils of a solenoid, custom superconducting dipole coils, iron pole-face magnets with shaped pole-faces, configurations of permanent magnets, or a combination thereof. In some embodiments, the accelerator may include an einzel lens configured to accelerate the particles from an initial magnetic field towards the tapered dipole magnet winding, the initial magnetic field being a zero or low magnetic field, the particles initially being low energy charged particles. In some embodiment, the particles may be reflected off a repelling electrode of the einzel lens into the tapered dipole magnet winding. In some embodiments, the particles include electrons, ions, or a combination thereof. In some embodiments, the particles may be accelerated in a low vacuum (i.e., a vacuum sufficiently low to allow unimpeded cyclotron motion). In some embodiments, the tapered dipole magnet winding may include superconducting magnets. In some embodiments, the tapered dipole magnet winding may be symmetrical around a plane extending through a central axis, each half of including a plurality of loops, each loop in the plurality of loops having a contoured rounded rectangular shape, each loop having one side that is substantially located at a first end, and where each loop has a different length. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a flowchart of an embodiment of a method. FIG. 2A is a graph showing a trajectory 200 of a deuterium ion in a balanced drift with an initial kinetic energy of 20 keV at 0.2 T going to 4.7 T region with 1 MeV final kinetic energy. Dashed