Research Case Study

Plasma Mg Evaporation Model

NH₃ plasma heating + EC–HT coupling across a 0–90 A current sweep.

COMSOL multiphysics model used to study Mg disc heating and evaporation behavior during NH₃ plasma exposure. A 0–90 A current sweep predicts thermal gradients and evaporation-risk trends across thickness cases to optimize nanoparticle production consistency and minimize parasitic Mg loss.

My contribution: built the EC–HT sweep model, meshing strategy, evaporation-proxy boundary condition, and IR thermography validation workflow. Experimental reactor hardware belonged to my advisor’s lab; the modeling workflow is my work.

Key result: thicker Mg discs reduced peak evaporation-risk sensitivity under equivalent current loading, identifying a more stable plasma heating regime.

Electric potential and current distribution used to compute Joule heating — **Electrical solution:** current paths used to compute Joule heating and resulting thermal gradients.

Engineering Implications

Thickness selection: compare Mg disc thickness cases
Gradient mapping: locate peak thermal regions
Evaporation control: evaluate Mg loss sensitivity
Model validation: IR thermography comparison

Simulation Setup

Coupled physics: Electric Currents + Heat Transfer
Current sweep: 0–90 A Joule heating load
Evaporation proxy: latent heat boundary
Radiation losses: Stefan–Boltzmann boundary

Next work: results informed later MgH₂ processing studies.

Model Geometry

Full assembly model — **Reactor domain assembly:** enclosure preserves realistic current return paths and boundary heat losses.

Mesh Strategy

Finite element mesh — **Mesh refinement:** dense elements near contacts and high-current regions, coarser outer domain to control computational cost.

Model assumptions & limits

Evaporation proxy: latent-heat sink boundary used as a relative Mg-loss indicator
NH₃ plasma: represented through enclosure boundary conditions rather than full plasma chemistry
Radiation: simplified Stefan–Boltzmann boundary treatment
Contact resistance: treated as a sensitivity parameter affecting peak gradients
Mesh convergence: checked to confirm key thermal trends were not dominated by element size

Experimental Reactor Hardware

**Tungsten boat:** evaporation hardware used in plasma experiments.

Magnesium discs — **Mg discs:** thickness-varied samples used for evaporation tests.

Reactor T pipe — **Reactor T-junction:** gas and electrical feed location motivating the model domain.

Further lab system details

The simulation work was grounded in a physical RF plasma reactor system used in the lab for Mg evaporation and nanoparticle synthesis. These images provide additional experimental context behind the geometry, operating constraints, and hardware assumptions used in the model.

Context note: the experimental reactor hardware belonged to my advisor’s lab. I included these photos as supporting lab context for the model, while the simulation workflow, coupling strategy, meshing, and validation logic shown above are my work.

RF plasma system overview — **System overview:** RF plasma reactor with rotational drive, vacuum interface, and controlled gas path.

Electrode clearance and isolation check — **Interface checks:** electrode spacing and electrical isolation verified prior to plasma ignition. Click image to view full figure.

Operational procedure: I authored a standard operating procedure (SOP) for safe plasma system startup, RF ignition, gas stabilization, and shutdown to ensure repeatable nanoparticle synthesis experiments.

Quartz-tube plasma reactor with rotational drive and furnace heating
RF electrode coupling and grounding configuration
Hydrogen and argon gas flow control with vacuum stabilization
Mechanical alignment and electrode-clearance verification prior to ignition
Startup, gas stabilization, RF ignition, and shutdown procedures documented for repeatable operation

Selected References

Kortshagen et al., Nonthermal Plasma Synthesis of Nanocrystals, Chemical Reviews.
Wagner et al., Low-Temperature Plasma Hydrogenation of Mg Nanoparticles, J. Appl. Phys.