The Effect of Excited Species on the Collisional Energy of Argon Inductively Coupled Plasmas: A Global Model Study

Global modeling of inductively coupled plasma (ICP) reactors is a powerful tool to investigate plasma parameters. In this article, the argon ICP global model is revisited to explore the effect of excited species on collisional energy through the study of different approaches to particle and energy balance equations. The collisional energy loss is much more sensitive to modifications in the balance equations than the electron temperature. According to the simulations, the multistep ionization reduces the collisional energy loss in all investigated reaction sets and the inclusion of heavy species reactions has negligible influence. The plasma parameters obtained, such as total energy loss and electron temperature, were compared with experimental results from the literature. The simulated cases that have more excited species and reactions in the energy balance are in better agreement with the experimental measurements.

A global model study of argon plasma chemistry used as propellant of a gridded ion thruster

The search for new propulsion devices for corrections and adjustments in the orbits of space systems composed of constellations of satellites in specific arrangements has progressively increased with the growth of requests for data transmission with greater speed and capacity. Electric propulsion is the best solution to reduce the propellant mass, in addition to allowing long mission times. Among the various types of thrusters, electrostatic thrusters have a better-defined physics, making possible the development of computational models for the study and optimization of their operational parameters. A global model was develed for a cylindrical ion thruster with the inductively coupled plasma (ICP) generator originated by the circulation of a radio-frequency current in an inductive coil that surrounds the thruster, having at the output a polarized grid extraction system accelerating the ionized argon gas (propellant). The global model is formed by charged and neutral particle balance equations and energy equations of electrons and gas. Neutral and excited species are accelerated by drift out of the thruster and ionized species accelerated for the reason of the electric field generated by the pair of polarized grids in direct current. The most in-depth study of argon plasma chemistry found that, among the various parameters that interfere with species density, the number of excited species has a direct influence on ionization, although it does not interfere much with ion density, what can be translated into a higher rate ion replacement, which is extremely important to gain thrust and specific impulse.

Photo-control of bimolecular reactions: reactivity of the long-lived Rhodamine 6G triplet excited state with ˙NO

Step-by-step photo-chemical mechanisms are becoming experimentally observable in extremely dilute environments as found in ion trap mass spectrometers where long lived excited species may react with controlled pressures of neutral reagents.