Propellants

HallThruster implements several common Hall thruster propellants, and makes it easy to implement your own.

Provided propellants

• Xenon
• Krypton
• Argon
• Bismuth
• Mercury

Implementing your own propellant

Propellants in HallThruster are instances of the Gas struct, which contains information about the atomic and thermodynamic properties of a gaseous species. These are

• name::String Full name of gas (i.e. Xenon)
• short_name::String Short name/symbol (i.e. Xe for Xenon)
• γ::Float64 Specific heat ratio / adiabatic index
• M::Float64 Molar mass (grams/mol) or atomic mass units
• m::Float64 Mass of atom in kg
• cp::Float64 Specific heat at constant pressure in J / kg / K
• cv::Float64 Specific heat at constant volume in J / kg / K
• R::Float64 Gas constant in J / kg / K

Many of these properties are inter-dependent, so HallThruster provides a convenience constructor Gas(name, short_name, γ, M) which will compute the rest of the properties automatically. For example, we might want to define atomic Neon:

using HallThruster: Gas

Neon = HallThruster.Gas("Neon", "Ne"; γ = 5/3, M = 20.1797)

# output

Neon

If we then selected Neon as a propellant in our Config struct and used one of the lookup table models for ionization, HallThruster.jl would know to search for files beginning ionization_Ne.... The same is true for excitation reactions (excitation_Ne...) and elastic collisions (elastic_Ne...). In addition to the reactions path in the HallThruster.jl directory, the user can specify other paths in which rate coefficient files can be found using the reaction_rate_directories option in the Config struct. These directories will be checked, in order, before the HallThruster.jl directory is checked. For example, if we passed `reactionratedirectories = ["reactions", "morereactions"], the code will first look in "reactions", then in "morereactions", before finally checking "HallThruster.jl/reactions". An error will be emitted if the reaction rate files cannot be found.