Magnetized Electron-Ion Collision and Rydberg Atom Formation Rates in Ultracold Plasmas

Ultracold neutral plasmas (UNPs) are excellent systems for studying basic plasma physics under well-characterized but also unusual plasma conditions. For example, plasmas in this work had temperatures within a few Kelvin of absolute zero. We have studied electron-ion collision rates in this project both as influenced by strong coupling and extreme magnetization. Theoretical investigations that built on prior AFOSR-funded experimental measurements showed that many-body-collisions are important for strongly-coupled plasmas, and without including those collisions theoretical predictions based only on binary collisions did not match our experimental measurements. We also report on the theoretical investigation of a heating mechanism in UNPs arising from applied DC electric fields. We have developed a new technique for measuring electron-ion collision rates through off-resonant RF heating rates that is a substantial improvement with regard to prior techniques that we used. We have used this technique to investigate electron-ion collision rates under extreme degrees of electron magnetization.