An instability in which neighboring flux tubes exchange positions across a pressure gradient or other stratification, reducing the appropriate potential energy. Unfavorable magnetic field-line curvature can drive the exchange; parallel variation bends the magnetic field and introduces stabilizing magnetic tension. In a steep-gradient low-plasma beta local Z-pinch, .
In the steep-gradient, low-plasma beta limit of kinetic magnetohydrodynamics, magnetic induction gives and . Therefore the forcing of the drift-kinetic equation is . It cancels the streaming operator on , leaving no leading kinetic phase mixing on this displacement branch. Freezing the parallel derivative to the equilibrium direction would lose this cancellation.
Articles by others on the same topic
Interchange instability, often discussed in the context of plasma physics and fluid dynamics, refers to a type of instability that can occur in systems where different fluids or plasmas with varying densities or properties are in contact with one another. This phenomenon is typically observed in situations where a denser fluid is above a lighter one, leading to the potential for buoyancy-driven instabilities. In more technical terms, interchange instability arises when gravitational or magnetic forces can lead to a configuration that becomes energetically unfavorable.