The ICP discharge running on the bench — vacuum chamber at left, probe and optical collection at right.
Overview
At the Stanford Plasma Physics Lab, I built RF self-compensating Langmuir probes from scratch to measure electron density, temperature, and electron energy distribution functions (EEDFs) — one for an inductively coupled plasma (ICP) and a second for an RF-magnetron thruster, and took measurements on both. The work was the experimental component of a DARPA-funded project characterizing radio-frequency driven plasmas for space propulsion.
Approach
- Designed tunable, rapidly swappable RF chokes for distortion suppression across 5–40 MHz, so one probe design could follow the drive frequency of either experiment.
- Built translating probe tips for spatially resolved measurements, sampling the ICP at ~21, ~26, and ~31 mm downstream of the coil region.
- Built an optical emission spectroscopy workflow to infer plasma properties from line ratios via an argon collisional-radiative model, cross-validating the probe results.
- Wrote the data-acquisition workflow behind both experiments, and redesigned and rebuilt the vacuum chamber around available equipment after an electronics failure — recovering over three weeks of schedule.
The probe tip translates downstream of the ICP region, giving spatially resolved measurements at ~21, ~26, and ~31 mm.
Why it matters
Cross-validating two independent diagnostics — the probe and optical emission spectroscopy — builds confidence in the measured plasma parameters and helps characterize discharges relevant to electric propulsion. The probe work was submitted to the 68th APS Division of Plasma Physics meeting.