Release notes

v0.20.0

New features

Support for molecular propellants and more general electron impact reactions. See Adding a new propellant for more information

Internal changes

Charges species are now printed with the charge in parentheses (i.e. Xe(2+) instead of Xe2+). This is to make the reaction format print exactly as it is parsed, and to disambiguate charged molecular propellants.

v0.19.0

Internal changes

Refactor ion and neutral internals to use a new FluidContainer struct. This means that plasmas containing multiple neutral species are now supported. This work lays the groundwork for molecular propellants.
With the above changes, the performance of the code has been increased by 25-35% on average.

Propellant struct

There is a new Propellant struct used to specify neutral gas properties at the anode.

Configuration changes

propellant is now propellants and can by an array of Propellant objects.
Anode mass flow rates as well as neutral properties at anode (temperature, velocity, etc) are now specified inside of Propellant objects. When using a single propellant, we provide a backwards-compatible interface.

Postprocessing changes

We have made several changes to stabilize the public interface and better isolate it from internal implementation details.

Added Frame and SpeciesState structs. See Outputs for more information.
No longer return the internal params struct in the Solution object.
Deprecating the old method of indexing by symbols. Instead, users should directly access fields of the Frame struct. A backwards-compatible interface is provided.

v0.18.7

Bug fixes

Make config.magnetic_field_scale work properly (it had previously done nothing, silently.)

v0.18.6

New features

Added molecular nitrogen (HallThruster.MolecularNitrogen) propellant along with ionization and elastic scattering cross sections.

A new ScaledGaussianBohm transport model has been added. This is a reparameterized version of the GaussianBohm model with non-dimensional parameters of order unity. See Anomalous transport for more details.

v0.18.3

Bug fixes

Fix indexing error in rate coefficient calculation
Fix massive divergence angles when ion velocity is zero or negative

v0.18.2

New features

Anomalous transport models

A new SimpleLogisticShift pressure shift model has been added. This is a simplified version of the LogisticPressureShift with one fewer parameter. See Anomalous transport for more details.

v0.18.1

Minor changes

Anomalous transport models

The pressure shift now only applies to the coefficients of the transport model as opposed to shifting the entire magnetic field. This was the pre-0.18.0 behavior.

v0.18.0

Breaking release

v0.18.0 is a breaking release, made as part of our effort to move toward v1.0.0 in the next few months. Users may need to update their code to avoid errors. Check out the list of changes and removals below to see how to migrate your code.

Major changes

Precompilation and load time

We have significantly reduced our load times by removing dependencies. We have also added a significant amount of additional precompilation work to reduce the time-to-first-simulation for most users.
With these improvements, HallThruster.jl may be suitable for use in a scripting workflow, depending on the expected run-time of your simulations.
For many users and workflows, the total time-to-first-simulation should be just a few seconds.

Exports

Xenon, Krypton, and time_average are no longer exported. Users will need to use the fully-qualified names, i.e. HallThruster.Xenon, HallThruster.Krypton, and HallThruster.time_average to access these variables. This can be made less verbose by bringing HallThruster into scope with a shorter name:

using HallThurster: HallThruster as het

het.Xenon

Postprocessing changes

The run_simulation function now takes an optional postprocess keyword argument, which takes a Postprocess object.
The Postprocess struct allows the user to specify time-averaging, saving, and output info. Any requested postprocessing will be performed automatically after the simulation has finished and output the requested JSON file.
See Postprocessing for more information

JSON IO

JSON input and output has been significantly reworded and enhanced. See Use JSON for input and output for more information. Users of the old JSON interface will need to update their input files to conform to the new format. Some of the changes include:

JSON inputs now map directly onto the Config structs used by HallThruster.jl elsewhere. The key names are now identical between the JSON input and the Config struct.
JSON outputs now contain all input used to run the simulation, including a Config (under key "config") and timestepping info (under key "simulation").
JSON outputs can be used to restart simulations, replacing the restart capability previously provided by JLD2.
Users can provide postprocessing directives in the JSON input by providing a "postprocessing" key in their input, following the Postprocessing interface introduced in this update.

The following keys have been renamed to better express the expected units.
- anode_Te -> anode_Tev
- cathode_Te -> cathode_Tev
- ion_temperature -> ion_temperature_K
- neutral_temperature -> neutral_temperature_K
- background_neutral_temperature -> background_temperature_K
- background_pressure -> background_pressure_Torr
- cathode_potential -> cathode_coupling_voltage
The following keys have been removed.
- min_electron_temperature (now set to the min(anode_Tev, cathode_Tev))
- min_number_density (now set to 1e6)
The following keys have had their options changed
- ionization_model: Formerly took a value of type IonizationModel, now takes a Symbol (one of :Lookup or :Landmark)
- excitation_model: Formerly took a value of type ExcitationModel, now takes a Symbol (one of :Lookup or :Landmark)
- electron_neutral_model: Formerly took a value of ElectronNeutralModel, now takes a Symbol (one of None, :Lookup or :Landmark)
See Configuration for a full list of options and default values.

Simulation changes

A new struct SimParams has been created to hold timestepping and grid generation options
run_simulation can now be called as run_simulation(config::Config, simparams::SimParams).
See Simulations for more information.

Solution changes

u has been removed from Solution
Solution.savevals has been renamed to frames
Solution.config contains the Config used to run the simulation
Solution.error captures any errors that are produced during a run
Retcode options have changed. The options are now :success, :failure, and :error. :success denotes a successful simulation, as before. :failure indicates a numerical instability, and :error captures any cases in which the simulation would have thrown an exception. The error text is captured in Solution.error.

Wall loss model changes

The parameter α of the WallSheath model has been renamed to loss_scale and has a default value of 1.0.
See Wall Loss Models for more information.

Grid generation changes

UnevenGrid no longer takes a custom density function as an input.
See Grid generation for more information.

Anomalous transport model changes

ShiftedTwoZoneBohm, ShiftedGaussianBohm, and ShiftedMultiBohm have been removed.
The model LogisticPressureShift has been added. This takes another anom model as a parameter and applies the same pressure-dependent shift as seen in these models.
To migrate to the new system, replace ShiftedGaussianBohm or similar with LogisticPressureShift(GaussianBohm(...), ...).
The dz and z0 parameters of LogisticPressureShift are now in terms of channel length rather than meters
Added the GaussianBohm model
Renamed the parameters of the ShiftedGaussianBohm/GaussianBohm model. The new parameters are:
- hall_min: the minimum Hall parameter
- hall_max: the maximum Hall parameter
- width: the width of the Gaussian subtraction from the Bohm-like transport model.
- center: the center of the Gaussian subtraction
See Anomalous transport for a full listing of anomalous transport options.

Thruster changes

Thruster.magnetic_field now takes a MagneticField object, which contains a filename, z-coordinates, and magnetic field values. Arbitrary functions are no longer supported. If only a filename is provided, the constructor will load the magnetic field from the provided file.
B_field_SPT_100 has been renamed to spt100_analytic_field
geometry_SPT_100 has been renamed to spt100_geometry
See Thrusters for more information.

Removals

The IonizationModel, ExcitationModel, and ElectronNeutralModel interfaces have been removed in favor of a simpler Symbol-based lookup system.
The GKElectronNeutral model has been removed entirely.
Serialization using JLD2 has been removed in favor of the JSON-based system described above.
Plotting capabilities are no longer provided by HallThruster.jl directly.