Luminescence Measurements of the Kr~+/Kr~(2+) + Kr Collision Systems

摘要

Emission excitation cross sections for collision processes relevant to krypton-fueled Hall effect thrusters are measured using optical emission spectroscopy in the 350-1000 nm spectral range. The most prominent emissions observed are in the near-infrared region from a low-lying excited electronic state of neutral Kr. In the case of Kr~+/Kr~(2+) + Kr systems, the emission cross section has a threshold at approximately 12.5 eV in the center-of-mass frame, and increases with collision energy until 200 eV where it remains constant through 600 eV. The energy profiles for emissions from Kr~+ ions vary considerably based on the collision partner. Threshold for these emissions is estimated at, in the center-of-mass frame, 40-50 eV for Kr~+ + Kr, <25 eV for Kr~(2+) + Kr, and between 29.9 and 34.4 eV for e~- + Kr. Potential diagnostic lines to be used for determination of electron temperatures and ion-energies are discussed.