Sven Andersson said:But, before those currents are produced, does the whole of the plasma "feel" the magnetic field?
Does not the plasma behave just like a piece of metal, where the behaviour of fields is well understood?Sven Andersson said:A magnetic field doesn't penetrate well into a plasma because it produces currents that counters the field, so to speak. But, before those currents are produced, does the whole of the plasma "feel" the magnetic field? For how long; ns, us or ms?
S.A.
Let's say we have a plasma in a Fusor, that is about the size of a golf ball, and apply a strong magnetic field; how long does it take for the currents to get running to shield the inner parts of the plasma from the field?Sven Andersson said:A magnetic field doesn't penetrate well into a plasma because it produces currents that counters the field, so to speak. But, before those currents are produced, does the whole of the plasma "feel" the magnetic field? For how long; ns, us or ms?
S.A.
The penetration depth of a magnetic field in a plasma depends on several factors such as the plasma density, temperature, and magnetic field strength. In general, the higher the plasma density and temperature, the shallower the penetration depth. Additionally, a stronger magnetic field will also result in a shallower penetration depth.
A magnetic field interacts with a plasma through the Lorentz force, which causes charged particles in the plasma to move in circular or helical paths around the magnetic field lines. This interaction is what allows the magnetic field to penetrate into the plasma.
No, a plasma cannot completely shield a magnetic field. However, a plasma can significantly reduce the strength of a magnetic field through the process of magnetic reconnection. This occurs when oppositely directed magnetic field lines in the plasma reconnect and cancel each other out, resulting in a weaker overall magnetic field.
The Alfvén speed is the speed at which magnetic waves can travel through a plasma. It is dependent on the density and magnetic field strength of the plasma. A higher Alfvén speed means that the magnetic field can penetrate deeper into the plasma before being slowed down or stopped.
In fusion experiments, the goal is to confine the plasma at high temperatures and densities for a sufficient amount of time to allow for fusion reactions to occur. The penetration of a magnetic field into the plasma affects this confinement by providing a means of heating and controlling the plasma, as well as preventing it from coming into contact with the walls of the fusion device. Therefore, understanding and controlling the penetration of the magnetic field is crucial for successful plasma confinement in fusion experiments.