Coulomb collision in fully ionized plasma

In a fully ionized plasma, Coulomb collisions play a significant role in determining the behaviour and dynamics of charged particles. Coulomb collisions are interactions between charged particles due to the electromagnetic forces between them. These collisions can lead to scattering, momentum exchange, energy transfer, and changes in particle trajectories within the plasma.

The likelihood of collisions between charged particles and neutral atoms when the plasma is mildly ionized leads to diffusion. However, when just ions and electrons are present in the plasma, all collisions are coulomb collisions between charged particles. There are two different ways that the coulomb collision might happen.

Case I: Collision between like particles (ion ion, electron electron collision)

If the collision is head on collision, particles emerges out with the velocities reversed, they simply interchanged their orbits and the guiding centre remain in the same place. However, if the collision was a 90° collision, the direction of the velocities altered by 90°. The centre of mass does not move, but the guiding centre does.

When neutral atoms and charged particles collide, the charged particles go on a random stroll following the collision, which causes diffusion.

Because of the intricate balance present in each ion-ion collision, very little diffusion results from the collision of like particles. For every ion that moves outward as a result of the collision, another one moves inward.

Case II: Collision between unlike particles

In the worst scenario, two particles with opposing charges collide 180 degrees and emerge with their velocities reversed. The guiding center will move in the same direction because they must gyrate about the line of force in the appropriate meaning. Since ions have a mass greater than that of electrons, when they collide, electrons bounce off of the almost motionless ions and proceed to move randomly as usual. Because they were frequently bombarded by electrons, the ions were somewhat displaced and moved outside. In this case, diffusion is caused by particle collisions.

Understanding and modeling Coulomb collisions in fully ionized plasmas are essential for accurately describing plasma behavior, predicting plasma properties, and designing plasma-based technologies. Various theoretical and computational approaches, such as the Boltzmann equation and kinetic simulations, are employed to study the effects of Coulomb collisions and their implications on plasma dynamics and behaviour.

Coulomb collisions in a fully ionized plasma have several important effects, including:

1. Momentum Transfer: During a Coulomb collision, momentum can be transferred between particles. This can lead to changes in particle velocities and can affect the overall plasma flow and momentum transport.

2. Energy Exchange: Coulomb collisions can also lead to energy transfer between particles. This energy transfer can result in changes in particle kinetic energies and can impact the plasma's thermal and energy transport properties.

3. Relaxation Processes: Coulomb collisions can drive the plasma towards a state of local thermodynamic equilibrium. Through collisions, particles can redistribute their energies and velocities, leading to Maxwellian velocity distributions and thermalization of the plasma.

4. Diffusion and Transport: Coulomb collisions contribute to particle diffusion and transport in a plasma. The scattering of particles by collisions can cause them to diffuse through the plasma and affect the overall transport of charged species.

5. Collisional Heating and Cooling: Coulomb collisions can lead to heating or cooling of the plasma depending on the relative energies and velocities of the colliding particles. In high-temperature plasmas, collisions can act as a heating mechanism, while in low-temperature plasmas, collisions can act as a cooling mechanism.

This note is a part of the Physics Repository.