Collisionality

In plasma physics of tokamaks, collisionality is a dimensionless parameter which expresses the ratio of the electron-ion collision frequency to the banana orbit frequency.

Definition

The plasma collisionality $\nu ^{*}$ is defined as^[1][2]

${\displaystyle \nu ^{*}=\nu _{\mathrm {ei} }\,{\sqrt {\frac {m_{\mathrm {e} }}{k_{\mathrm {B} }T_{\mathrm {e} }}}}\,\epsilon ^{-3/2}\,qR,}$

where $\nu _{{\mathrm {ei}}}$ denotes the electron-ion collision frequency, $R$ is the plasma major radius, $\epsilon$ is the inverse aspect-ratio, and $q$ is the safety factor. The plasma parameters $m_{{\mathrm {i}}}$ and $T_{{\mathrm {i}}}$ denote, respectively, the mass and temperature of the ions, and $k_{\mathrm {B} }$ is the Boltzmann constant.

See also

• List of plasma (physics) articles

References

1. Nucl. Fusion, Vol. 39, No. 12 (1999)
2. Wenzel, K and Sigmar, D.. Nucl. Fusion 30, 1117 (1990)