Investigation of photoplasma that is configured in an electrostatic extractor having high-temperature electrodes

In the present work we report the investigation of photoplasma in a high temperature electrostatic extractor. The extractor can operate at temperatures ~900 K, at electric field ~200 V/cm and in an environment where there is metal vapor and photon flux. It is used concurrently with another vapor generating furnace that is placed below it. It is observed that for operation over long duration (~5 h) barium atoms from the vapor-producing furnace coat the electrodes. They are re-evaporated from the hot electrodes thereby forming a collision-less vapor cell between them. Multi-step, multi-wavelength resonant ionization process using lasers produce photoplasma in the cell. Thermionic emission from barium coated hot electrodes provides the seed current flux for electron-impact ionization of the atoms in the cell. The ionized background plasma provides a steady state current between the electrodes. The transient photoplasma motion is superimposed on it. The photoions decay as the ions are collected. The Bohm current and current due to sheath boundary motion determines their evolution.