Introduction

Hermes-3 is a plasma simulation model built on BOUT++, developed mainly for simulating the edge of magnetically confined plasmas such as tokamaks. The source code is available on Github. The main aim of this model is multi-species simulation of fusion reactors, where the plasma will contain a mixture of deuterium, tritium, helium and other species.

An unusual feature of this model is that it is organised into reusable components, which can be tested individually and then configured at run-time. For example a transport simulation with deuterium and tritium ions and atoms has an input file specifying the components

[hermes]
components = d+, d, t+, t, e, collisions, sheath_boundary, recycling, reactions

The governing equations for each species are specified e.g.

[d+]
type = evolve_density, evolve_momentum, evolve_pressure, anomalous_diffusion
AA = 2   # Atomic mass
charge = 1

and other components have their configuration options e.g. for reactions

[reactions]
type = (
        d + e -> d+ + 2e,   # Deuterium ionisation
        t + e -> t+ + 2e,   # Tritium ionisation
       )