Michael Mercier / UAH
Producers utilizing plasma processes in semiconductor manufacturing and supplies processing could have a brand new device to keep away from undesirable plasma stratifications utilizing a pc striations mannequin developed by The College of Alabama in Huntsville (UAH) and CFD Analysis Corp (CFDRC).
“The striations we’re speaking about are seen in noble gases in some contexts,” says Dr. Vladimir Kolobov, a principal analysis scientist within the Middle for Area Plasma and Aeronomic Analysis (CSPAR) at UAH, part of the College of Alabama System. He has been finding out them for 30 years. The noble gases are helium, neon, argon, krypton, xenon and mixtures of them.
For instance, striations are invisible to the bare eye as they transfer quick by the neon fuel used inside fluorescent mild tubes, he says, however they are often simply visualized utilizing a stroboscopic approach.
“What we’re speaking about is one thing that for 200 years individuals may see, however solely very lately may they be seen in pc simulations,” Dr. Kolobov says.
In reality, the intense and darkish layers of striations have been noticed in fuel discharges lengthy earlier than Dr. Irving Langmuir launched the time period plasma, he says.
“Now we have used a self-consistent hybrid mannequin of collisional plasma to acquire transferring striations in DC discharges of noble gases,” Dr. Kolobov says.
“The calculated properties of self-excited waves in neon and argon agreed with out there experimental knowledge, and the origin of a helium plasma stability resulting from stratification was clarified. A simplified two-level excitation-ionization mannequin has been used, neglecting the nonlinear results resulting from stepwise ionization, fuel heating and Coulomb interactions amongst electrons.”
The brand new mannequin supplies insights into the circumstances underneath which stratifications kind.
“When you possibly can develop a pc mannequin and reproduce them, then that you just perceive this course of,” Dr. Kolobov says.
The analysis was funded by the Nationwide Science Basis’s Established Program to Stimulate Aggressive Analysis (EPSCoR) Future Applied sciences enabled by Plasma Processes (FTPP) initiative and its predecessor, Connecting the Plasma Universe to Plasma Know-how in Alabama (CPU2AL). Each grants are led by UAH.
Additional developments of the mannequin will enable examine of the transitions between completely different wave sorts noticed experimentally in noble gases.
“Increasing the plasma-induced chemistry will allow finding out the experimentally noticed striations in molecular gases and fuel mixtures,” Dr. Kolobov says. “The supply of a pc mannequin for stratified plasma will assist choose acceptable discharge circumstances for particular functions.”
The brand new mannequin is step one in making a system that may assist producers create the sorts of discharge circumstances that don’t encourage the event of plasma stratifications of their plasma-based manufacturing methods, Dr. Kolobov says.
The work pertains to house science research at CSPAR as a result of photo voltaic wind plasma is wholly ionized however its properties have many issues in widespread with weakly ionized fuel discharge plasmas, so the mannequin will also be relevant to house climate forecasting.
“Now we have beforehand proven that electron kinetics in photo voltaic wind plasma has many features in widespread with electron kinetics in fuel discharges,” Dr. Kolobov says. “The grid-based kinetic solvers can be utilized for collisional gas-discharge plasma and collision-less magnetized house plasmas. They’ve already been demonstrated for electron kinetics within the photo voltaic wind.”
“The twin utility of plasma fashions corresponding to this illustrates the each the strengths of the UAH and CFDRC partnership and the significance of cross-disciplinary collaboration, which is likely one of the necessary targets underlying the FTPP grant that helps 9 establishments throughout Alabama, together with UAH and CFDRC,” says Dr. Gary Zank, the Aerojet Rocketdyne chair of UAH’s Division of Area Science, director of CSPAR and the principal investigator for the FTPP and CPU2AL grants.
“The event of an electron kinetic mannequin for the photo voltaic wind led to a major advance in our understanding of how energetic electrons created within the environment of the solar carry vitality to the Earth and past,” Dr. Zank says. “It’s gratifying to see associated principle and modeling being profitable when utilized to sensible manufacturing issues involving fuel discharges.”
The analysis was made potential by growing grid-based kinetic solvers for electrons in low-temperature collisional plasmas. The development of hybrid kinetic-fluid solver fashions is likely one of the foundational analysis focus areas within the new FTPP venture.
“Now we have pursued the event of such solvers for nearly 25 years at CFD Analysis Corp. and UAH,” says Dr. Kolobov. “Lastly, we now have developed one thing that was not potential once I began finding out this plasma stratification drawback 30 years in the past in my PhD work, which is why I’m so enthusiastic about it.”
The brand new solvers will even enable higher forecasting of house climate storms, the main focus of an ongoing NASA SBIR Part 2 venture implementing a novel Radiation, Interplanetary Shocks & Coronal Sources toolset at CFD Analysis and UAH, he says.
The analysis used business COMSOL and open-source software program put in on UAH pc methods. The publication-quality figures have been produced with Tecplot software program out there at CSPAR.