Magnetic Confinement
The trapping of high-temperature fusion plasma using intense magnetic fields that exert Lorentz forces to prevent plasma particles from contacting container walls.
Governing formula
β = p / (B² / (2 μ₀)) = 2 μ₀ n k_B T / B²
SI unit
Dimensionless Ratio (Plasma Beta β)
In depth
Because 100-million-degree fusion plasmas would melt any solid wall, magnetic fields force charged ions and electrons into tight helical orbits around magnetic flux lines, insulating the hot core from vacuum vessel boundaries.
Examples in the real world
Confining thermonuclear fusion plasma in Tokamaks, Stellarators, and Magnetic Mirror devices.