Plasma Controls, LLC (SBC) and Colorado State University (RI) will mature an energy and species plasma diagnostic for use with plasma thrusters. The combined Energy and Velocity Analyzer for Distributions of Electric Rockets, or the ‘E-VADER’, is needed especially for characterizing the plasma plume of Hall thrusters, where researchers desire to know ion energies and charged species fractions emitted from the plume region. When used as a standalone device, traditional species analyzers called ExB probes or Wein filters, which filter particles according to their velocity, can have overlapping signal features due to the unique energy and charge distribution functions of Hall thrusters – specifically wide energy ranges and large concentrations of multiply-charged species. These characteristics make analysis of traditional diagnostic tools impossible. Plasma Controls and CSU will combine an electrostatic energy analyzer (ESA) to the front end of an ExB velocity filter that will allow researchers to measure in high fidelity not only the ion energy per charge distribution (E/q), but also the charge state fraction (q) at any, arbitrarily selected energy. The diagnostic can additionally be used to differentiate charged particles of different mass, such as in modern propellants like water and iodine (distinguishing H+ vs O2+, or I2+ versus I+ for example). The E-VADER probe is tolerant of a wide range of propellants and power density because it is fabricated primarily of graphite, which has an increased resistance to corrosion, sputtering, and heat. We will combine our existing ESA and ExB diagnostics into an easily configurable device for testing in Phase I with an aim toward developing a well-understood, calibrated, trouble-free, and straightforward-to-use research and analysis tool in Phase II for both non-specialist and advanced customers.
E-VADER will allow NASA to measure energy and species fractions in plumes of research and flight thrusters that create charged species with wide energy distribution, such as those generated by state-of-the-art magnetically-shielded Hall thrusters. Furthermore, E-VADER will significantly simplify data analysis, especially in thrusters where traditional approaches to measuring fractions of multiply-charged species fail. Finally, E-VADER can be used on high power devices and on alternative propellants including H2O, I2, Li, Hg and others.
NASA thrusters have plasma source doppelgangers in ground-based plasma processing applications, and the developed diagnostic can be used to characterize the plasma plumes of many devices, including ion sources, end-Hall sources, and magnetrons. In ground-based processing, multiple gas species are used including argon and oxygen, which can be characterized by Plasma Controls’ diagnostic tools.