How is current induced in the plasma in a tokamak?

[Jan Berkhout]

For a Year 12 Assignment I have to do a seminar on how magnetic fields are involved with a certain topic. I chose nuclear fusion energy production and specifically the tokamak. I understand that a toroidal magnetic field is created when a current is sent through a solenoid wrapped in a torus. And that in nuclear fusion, this field forces the plasma to move in circular motion around the tokamak. But, in a tokamak, from my understanding, another solenoid is placed vertically in the center of the tokamak. Apparently sending a current through this solenoid induces a current in the plasma. How does it do this? Is it because the magnetic field generated from the center solenoid interacts with the toroidal magnetic field and changes its strength, therefore creating a current in the wire? How is current induced in the plasma in a tokamak?

 

[phyzguy]

For a Year 12 Assignment I have to do a seminar on how magnetic fields are involved with a certain topic. I chose nuclear fusion energy production and specifically the tokamak. I understand that a toroidal magnetic field is created when a current is sent through a solenoid wrapped in a torus. And that in nuclear fusion, this field forces the plasma to move in circular motion around the tokamak. But, in a tokamak, from my understanding, another solenoid is placed vertically in the center of the tokamak. Apparently sending a current through this solenoid induces a current in the plasma. How does it do this? Is it because the magnetic field generated from the center solenoid interacts with the toroidal magnetic field and changes its strength, therefore creating a current in the wire? How is current induced in the plasma in a tokamak?

It is basically just a transformer. Are you familiar with how a transformer works? The changing current in the primary winding creates a changing magnetic field, which induces a current in the secondary winding. A Tokamak works the same way. A changing current (usually just a linear ramp) is sent through the primary solenoid, which creates a magnetic field which increases with time. The plasma acts as the secondary winding, so the changing magnetic field induces a current to flow in the plasma.

 

[Jan Berkhout]

It is basically just a transformer. Are you familiar with how a transformer works? The changing current in the primary winding creates a changing magnetic field, which induces a current in the secondary winding. A Tokamak works the same way. A changing current (usually just a linear ramp) is sent through the primary solenoid, which creates a magnetic field which increases with time. The plasma acts as the secondary winding, so the changing magnetic field induces a current to flow in the plasma.

Thank you! This is a great help!