The primary communication channel for PlasmaPy is our Matrix chat room. There is also a Gitter bridge to this chat room.
PlasmaPy's GitHub Discussions page is a great place to suggest ideas, bring up discussion topics, and ask questions in threaded public discussions.
We also have a low traffic mailing list for occasional announcements and infrequent discussions.
We have a suggestion box if you would like to (optionally anonymously) suggest a feature/topic for consideration. These will be reposted as GitHub issues, as appropriate, for further discussion.
Please check PlasmaPy meetings for regularly scheduled meetings and special events. The regularly scheduled meetings include a community meeting to discuss code development, a project meeting to discuss broader aspects of the PlasmaPy project like education and outreach to the broader plasma community, and meetings of PlasmaPy working groups. The special events include Plasma Hack Week.