Kinetic Theory
Particle Distribution Function
Density Function ns Number density, mass density, charge density
The Boltzmann Equation: time variation of a distribution function
Total Derivative in Phase Space
Homework Problem 3.6, 3.7, 3.8
Examples of Distribution Functions
Maxwellian Distribution Functions
One-dimensional Maxwellian, cont’d
Thermal speed
Equilibrium Distribution charge x voltage = energy
Velocity Moments
Bulk flow velocity
Pressure tensor
Scalar pressure
Heat Flux
Continuity equation: 0th moment of B-equation
Momentum Equation: 1st moment of B-equation
The momentum equation
Pressure Gradient Force
Pressure as Thermal Energy Density
Charge and Current Densities
Moments Measurements in Space Physics Particle detector measures electric current produced by the charged particles The electric field current, count-rate, is converted to number of density flux according to calibration The flux can be converted to distribution function The detector can select the energy range with energy resolution, as well as type of the particle species Each detector has a finite field angle which determines the spatial resolution The detector(s) scan over directions Fluxes from all energy channels and all looking directions can be added together. Moment factor can be added in the integration process to obtain moments, which are used as macroscopic quantities, such as density, velocity, temperature, (temperature) anisotropy Satellite charge is a major problem in deriving correct distribution function In the existence of multiple populations, “moments” may mean different things. Distribution functions have to be examined in this case.