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Magnetic pressure
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Fields exert pressure on plasma.
Magnetic fields exert pressure P = B²/2μ₀ and tension along the field lines, important in plasmas and stars. At 1 T the pressure is 4 atm.
Tokamaks confine plasma with magnetic pressure.
Sunspots are regions of strong fields.
In more detail
A magnetic field exerts pressure on its boundaries, equal to B²/(2μ0). Strong fields can compress plasmas and support structures such as the magnetic pressure of the Sun's corona.
Real-world uses
- Fusion reactors use magnetic pressure to confine hot plasma.
- Astrophysics uses magnetic pressure to model stars and coronae.
- Plasma physicists use magnetic pressure to confine hot plasma inside fusion reactors.
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Frequently asked questions
Is magnetic pressure the same as energy density?
Numerically yes, since the pressure equals the energy density for a magnetic field.
Why does it matter for plasmas?
It can balance the pressure of hot plasma and hold it in place.
How can a magnetic field hold a plasma?
The field exerts a pressure that balances the outward pressure of the hot plasma, keeping it confined.
Related topics in Magnetism & Induction
Magnetic field of moving charge · Hall effect and sensors · Magnetic energy density · Lorentz force law · Magnetic shielding