Collisionality

In Plasma Physics, collisionality is a dimensionless parameter proportional to the ion-ion collision frequency

Definition

The plasma collisionality ν ^* is defined as^[1]:
$\nu^* = \nu_{ii}\sqrt{\frac{m_i}{k_B T_i}}\epsilon^{-3/2}qR$
where ν_ii denotes the ion-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_i and T_i denote, respectively, the ion mass and ion temperature, and k_B is the Boltzmann constant.

References

1. ^ Nucl. Fusion, Vol. 39, No. 12 (1999)