Editing Hall effect (section)

=== Hall effect in ionized gases ===
The Hall effect in an ionized gas ([[Plasma (physics)|plasma]]) is significantly different from the Hall effect in solids (where the '''Hall parameter''' is always much less than unity). In a plasma, the Hall parameter can take any value. The Hall parameter, {{math|''β''}}, in a plasma is the ratio between the electron [[Gyroradius|gyrofrequency]], {{math|''Ω''<sub>e</sub>}}, and the electron-heavy particle collision frequency, {{mvar|ν}}:
<math display="block">\beta=\frac {\Omega_\mathrm{e}}{\nu}=\frac {eB}{m_\mathrm{e}\nu}</math>
where
* {{math|''e''}} is the [[elementary charge]] (approximately {{val|1.6e-19|ul=C}})
* {{math|''B''}} is the magnetic field (in [[tesla (unit)|teslas]])
* {{math|''m''<sub>e</sub>}} is the [[electron|electron mass]] (approximately {{val|9.1e-31|u=kg}}).

The Hall parameter value increases with the magnetic field strength.

Physically, the trajectories of electrons are curved by the [[Lorentz force]]. Nevertheless, when the Hall parameter is low, their motion between two encounters with heavy particles ([[Neutral particle|neutral]] or [[ion]]) is almost linear. But if the Hall parameter is high, the electron movements are highly curved. The [[current density]] vector, {{math|'''J'''}}, is no longer collinear with the [[electric field]] vector, {{math|'''E'''}}. The two vectors {{math|'''J'''}} and {{math|'''E'''}} make the '''Hall angle''', {{mvar|θ}}, which also gives the Hall parameter:
<math display="block">\beta = \tan(\theta).</math>