We cool our experiment to 10 K in the hope that the plasmas will also reach this temperature eventually.
But the final temperature T_{f} of any cooled body also depends on the ratio of cooling rate Γ to heating power H:

Γ is the rate of equilibration with the thermal bath at 10 K: it takes a time t = Γ

H is the amount of energy per unit time which the plasma absorbs due to radial expansion and RF noise on the electrodes. H is about 50 K s

To reach the lowest plasma temperatures, we need to minimize H and maximize Γ. We have successfully increased Γ
by over an order of magnitude by coupling the electron cyclotron motion to a microwave cavity.

The microwave cavity traps a set of electromagnetic modes, each with a characteristic frequency. When we tune the magnetic field B so that the electron cyclotron frequency eB/m matches the frequency of a cavity mode, the cavity can absorb cyclotron energy from the electrons, and the plasmas cool more quickly.

See our latest publication in Physical Review Letters on the publications page.