Ion cyclotron waves are set up in a toroidal plasma (previously formed by Ohmic heating) contained in the Model C stellarator, and absorbed at local minima in the confining magnetic field. The plasma (1012−1013cm−3) confined in these magnetic mirrors under certain conditions has little interaction with the main body of the plasma; the perpendicular ion temperature can reach several keV, while the electrons remain at less than 100 eV. We can thus reach a regime not yet available to other mirror confinement experiments. The observed cooling of the plasma in the mirrors agrees with the calculated ion‐ion and ion‐electron loss processes and charge exchange. At the highest temperatures and lowest densities, the confinement time in the mirrors is limited to ∼ 1 msec, most likely by charge exchange with a steady influx of neutral hydrogen. We find no evidence for any anomalous particle‐ or energy‐loss process, although several instabilities are predicted by theory to occur.