Coupled inter-species sources

Coupled sources operate on several block states at the same time. Declare them as typed operators on the model layer, then consume the returned handle in a pops.time.Program.

T = Program("coupled_step")
e = T.state("Ue", block="electrons")
i = T.state("Ui", block="ions")

fields = T.solve_fields_from_blocks([e.n, i.n])
rates = collision_operator(e.n, i.n, fields)

T.define(e.next, e.n + T.dt * rates["electrons"])
T.define(i.next, i.n + T.dt * rates["ions"])
T.commit_many({"electrons": e.next, "ions": i.next})

The operator handle is a typed object returned by model authoring. Do not reference coupled operators with string names in public program code.

Use the same program with Uniform(...) or AMR(...) layouts when the source descriptor declares both routes.