What is Fusion?

Why Fusion?

• Inexhaustible Energy
• Potentially cleaner than fission
• Space Exploration
• …

The Next Logical Step

How do we do Fusion?

• Gravitation Confinement
• Inertial Confinement
• Magnetic Confinement

The Sun confines plasma with its gravity

Inertial Confinement Fusion - The Easy Way

Inertial Confinement with a Laser

Confinement with Electric Current: Z Machine

Magnetic Confinement: The Tokamak ITER

Challenges for the Tokamak

• Disruptions
• Magnetic Field Gradient
• Plasma Current

A Conceptual Design:

Tokamak style fusion reactors have been the dominant type in plasma physics experiments. Many of the disruptions and drifts that plague this type of reactor tend to flow in the direction of decreasing magnetic field. Since the magnetic field is stronger nearer to the center of the tokamak, disruptions and drifts cause plasma to flow away from the center. A feature of the tokamak used to combat this effect is to have a current flowing within the plasma so that the magnetic field lines twist so that the drifts are averaged as sections of plasma spend some time close to the center and some time far from it. Since drifts and disruptions tend to flow in the direction of decreasing magnetic field, some confinement schemes have been suggested to keep the plasma in a low field region so that the plasma would have to move through a higher field region to escape the device. Continue...

A Conceptual Design:

This conceptual design employs two toroidial coils, inner and outer, in such a way that the inner coil creates a void in the magnetic field generated by the outer coil. This allows for a low field region in which the plasma can become homogenized. Any path leading out of the low field region requires the plasma to move in the direction of increasing magnetic field. The inner coil also provides the field otherwise generated by plasma current in a tokamak, so there is no need to induce a current in the plasma. Since the inner coil is submerged in the plasma, the turns of the coil are spaced out so that the field generated shields the inner coil from the plasma. Single particle simulations were conducted on this design that show particles being confined indefinitely. Magneto hydrodynamic (MHD) simulations will be warranted if there is significant interest in this design.

The Concept: Perspective View

The Concept: Top View

Magnetic Surfaces at the Midplane

Magnetic Field Magnitude

The Simulated Path an Ion Takes in the Reactor

A Simulation Rendered in DirectX

Future Work

Ultimately MHD simulations will be needed to validate the merit of the design. Short of this, it’s possible that a scale model can be tested on lower temperature plasmas. A support system (or levitation system) for the inner coil will need to be developed. The supports may need to be magnetically shielded since they will have to pass through a region containing plasma. It’s possible the plasma density will be low enough on the inner edge of the inner coil (where the magnetic field is highest) for supports to be placed there without having to divert the plasma with magnetic shielding or otherwise.