Polaris has been operating at low power already. They have recently installed shielding in the walls to allow higher power operation.

There seems to be a fair bit of progress notes from them. They aren't obligated to tell us anything, of course.

Here are their funding rounds.[1] Their funders, which include both YC and DoD, had better be getting info.

[1] https://tracxn.com/d/companies/helion/__fS6qGKScel2LE9EV85bG...