Particle beam injection system

• US 4,065,351 A
• Filed: 03/25/1976
• Issued: 12/27/1977
• Est. Priority Date: 03/25/1976
• Status: Expired due to Term

• Current Assignee: The United States of America as represented by the United States Energy Research and Development Administration
• Original Assignee: The United States of America as represented by the United States Energy Research and Development Administration
• Inventors: Kulsrud, Russell M., Jassby, Daniel L.
• Primary Examiner(s): Engle, Samuel W.
• Assistant Examiner(s): Cangialosi, S. A.
• Application Number:
  US05/670,480
• Time in Patent Office: 642 Days
• Field of Search: 176/1, 176/3, 176/4, 176/5, 176/9, 176/2, 315/111.1-111.7
• US Class Current: 376/107
• CPC Class Codes: G21B 1/13 First wall; Blanket; Divertor
• CPC Class Codes: H01J 37/32 Gas-filled discharge tubes heating by discharge H05B
• CPC Class Codes: Y02E 30/10 Nuclear fusion reactors

Abstract

This invention provides a poloidal divertor for stacking counterstreaming ion beams to provide high intensity colliding beams. To this end, method and apparatus are provided that inject high energy, high velocity, ordered, atomic deuterium and tritium beams into a lower energy, toroidal, thermal equilibrium, neutral, target plasma column that is magnetically confined along an endless magnetic axis in a strong restoring force magnetic field having helical field lines to produce counterstreaming deuteron and triton beams that are received bent, stacked and transported along the endless axis, while a poloidal divertor removes thermal ions and electrons all along the axis to increase the density of the counterstreaming ion beams and the reaction products resulting therefrom. By balancing the stacking and removal, colliding, strong focused particle beams, reaction products and reactions are produced that convert one form of energy into another form of energy.

Claims

1. Apparatus for injecting charged particles into a confining magnetic field, comprising:

a. vacuum tight housing means having an endless z first circular axis, and entrance ports and exit ports forming solid collecting walls out of the line of sight with the axis but communicating therewith through poloidal apertures in the sides of the housing means;

b. vacuum pump means communicating with the collecting walls;

c. means for forming a confining, toroidal, magnetic field having helical field lines forming inner and outer concentric magnetic surfaces centered on an endless magnetic second axis concentric with the first axis in the housing means;

d. means for forming an equilibrium, neutral, thermal, target plasma column of disassociated electrons, tritons, and deuterium ions that are confined by the magnetic field in the column in the container means along the magnetic second axis at an elevated temperature that causes the ions to diffuse by collisions outwardly away from the magnetic axis toward the vacuum container means;

e. means for continuously injecting neutral atomic beams of deuterium and tritium through the entrance ports along parallel trajectories in the plane of the circular axis at energies above the average energy of the plasma sufficient to penetrate the sides of the plasma column to a depth for producing thermal electrons and deuterons and tritons at energies of at least 10 keV above the average energy of the confined target plasma column, the injection forming fast, ordered, high energy, high velocity counterstreaming deuterons and tritons that drift along the helical field lines, and circulate around the length of the axis, these counterstreaming deuterons and tritons forming beams having distinct ion velocity distributions that are oppositely displaced in velocity along the magnetic axis, while the helical field lines provide strong restoring forces that maintain the directedness of the fast deuterons and tritons along the magnetic axis, some of said fast deuterons and tritons slowing down to the average energy of the confined target plasma column thereby to maintain the plasma density and temperature by balancing the diffusion rate; and

f. divertor means communicating with the field lines of the outer magnetic surfaces through the poloidal apertures for collecting diffusing plasma particles through the exit ports from the outside of the plasma column and burying them in the vacuum pump means so as to maintain a high counterstreaming deuteron and triton number density.

2. Method for injecting charges particles into a tokamak confining magnetic field, comprising:

a. Magnetically confining a neutral, toroidal plasma column of ions and electrons having a thermal temperature, density, volume, average thermal energy and average confinement time along an endless magnetic axis in a tokamak vacuum container means containing a toroidal magnetic field having concentric magnetic field lines of force forming a magnetic container that is concentric with the magnetic axis and capable of confining the plasma for a sufficient period of time to produce a thermal ion diffusion loss rate and a thermal electron diffusion loss rate;

b. injecting ordered, neutral, atomic beams having fast ordered ions and orbital electrons at densities that are directed into the confined plasma with trajectories that are generally tangent to the magnetic field lines and azimithally along the magnetic axis in the same and the opposite direction to the direction of the magnetic axis at an energy that is greater than the average thermal energy of the confined plasma, the neutral beams interacting with the confined thermal plasma ions to inject fast ions and thermal electrons into the plasma, the fast ions forming oppositely circulating, counterstreaming ion beams having directed, distinctly ordered, ion velocity distributions and associated beam currents that are oppositely displaced in velocity along the magnetic axis, the latter ion beams injecting thermal ions into the confined plasma due to the slowing down of the ion beams in the confined plasma;

c. the magnetic confinement maintaining the aforesaid thermal electron injection in balance with the thermal electron diffusion to maintain a thermal electron density in the confined plasma;

d. the magnetic confinement of the plasma also maintaining the directedness of the counterstreaming ion beams until the ions therein slow down to the average thermal energy of the confined plasma; and

e. removing the diffusing thermal electrons and the ions that slow down to the average thermal energy of the confined plasma, said removal being at least as fast as the average time it takes for the thermal ions to slow down to the average thermal energy of the confined plasma so as to maintain a high counterstreaming ion number density in the counterstreaming ion beams that is at least as great as the confined thermal ion density, said removal also maintaining the sum of the aforesaid counterstreaming ion number density and the confined thermal ion density substantially in balance with the confined electron density in the confined plasma so that the counterstreaming ion beams continuously produce a large number of head-on collisions between the counterstreaming ions all along the magnetic axis.

3. The method of claim 2 in which opposite deuterium and tritium neutral atomic beams are injected into the confining magnetic field to produce counterstreaming deuteron and triton beams that are tied to the magnetic field lines of force along trajectories that spiral helically along axes that are centered on the respective field lines.

4. The method of claim 3 in which the confined plasma has a weight of at least one gram at an electron temperature T_e ≧

1 keV and a density n_e ≧

10¹² cm^-3.

5. The method of claim 4 in which the removal of the thermal ions is provided by a divertor for selectively decreasing the number of relatively cold ions confined in the magnetic field all along the magnetic axis.

6. The method of claim 5 in which a plasma current is provided along the endless magnetic axis for twisting the field lines into helixes that helically twist around the magnetic axis.

7. The method of claim 6 in which the input and output are balanced to maintain a counterstreaming ion number density that is 50% of the electron number density of the confined plasma.

8. The method of claim 7 in which counterstreaming deuteron and triton beams collide to produce neutrons in the confined plasma along the length of the magnetic axis.

9. The method of injecting charged particles into a confining magnetic field, comprising the steps of evacuating a vacuum container means having an endless equilibrium axis to a vacuum of at least 3 ×

10^-5 torr;

forming a magnetic field having concentric magnetic surfaces along a magnetic axis and field lines concentric with the magnetic axis that are co-axial with the equilibrium axis in the vacuum container means;

admitting at least one gram of a gas containing tritium and deuterium into the vacuum container means to a density of at least 10¹² particles/cm³, ohmically heating the gas to a temperature of at least 1.0 keV to produce an equilibrium target plasma column containing thermal ions and electrons that are confined at a number density of at least 10¹² particles/cm³ in the magnetic field in the vacuum container means along the magnetic axis for at least 1 msec, injecting high energy, high velocity, ordered neutral atomic deuterium and tritium beams into the target plasma in the same and the opposite direction to the direction of the magnetic axis at energies of at least 10 keV greater than the energy of the confined plasma and at currents of at least 1μ

A to produce ordered, high energy, high velocity counterstreaming deuterons and tritons with like high energies and velocities, the counterstreaming deuterons and tritons having number densities higher than the density of the injected beams and distinct ion velocity distributions that are oppositely displaced in velocity along the magnetic axis while the magnetic field maintains the directedness of the counterstreaming deuterons and tritons along the magnetic axis until they slow down to the average energy of the confined equilibrium target plasma column, and diverting thermal electrons and ions away from the outside of the plasma column into a poloidal divertor for burial therein.

10. Method for injecting charged particles into a confining magnetic field, comprising the steps of:

a. producing a thermal plasma column in a vacuum tight housing;

b. confining the plasma along a circular axis in a toroidal magnetic field in the vacuum tight housing;

c. injecting equal momentum, neutral atomic beams through the sides of the housing along parallel trajectories in the plane of the circular axis at energies above the average plasma energy sufficient to penetrate the outside of the plasma column to a depth for producing counterstreaming ion beams that slow down to the average energy of the thermal plasma and drift across the toroidal magnetic field in a direction away from the axis by diffusion;

d. continuing the injection for a period sufficient to stack the counterstreaming beams for many orbits around the length of the axis at a rate in balance with the diffusion rate; and

e. removing the thermal plasma particles that drift across the magnetic field by diffusion by magnetically diverting them through poloidal apertures in the sides of the housing selectively to neutralize the particles outside of the plasma column and out of a line of sight therewith for maintaining high counterstreaming ion beam densities.