Circle Symbol of Water

In a magnetic field, any moving particles are forced to spiral along the magnetic field lines, because they are charged. So, if you create a circular magnetic field, then plasma particles will be trapped, perpetually circulating around the loop.

Magnetic Field

This drawing illustrates this rule. The red line is a segment of a wire and the arrow designates the direction of the current, I. The blue circles represent the magnetic field lines, B, and the arrow heads signify the direction of the magnetic field. Physicists agree that the magnetic field goes from north to south.

In an electric current any moving charge creates a magnetic field. A changing magnetic field causes current to flow in a conductor in a closed circuit. More precisely, a changing magnetic field creates an electric field and an electric field causes charged particles to move.

If the electron and the proton (or other positive ion) were free, they would simply move in those directions. But they are not free, because of the magnetic force.

If only magnetic forces were present (no electric field), the proton would circle around a magnetic field line in the clockwise direction (from where we are looking) and the electron in the counter-clockwise direction. These directions are given near the left edge of the drawing.