Undergraduate Honors Theses

Thesis Defended

Fall 2014

Document Type


Type of Thesis

Departmental Honors



First Advisor

Robert Ergun


The Colorado Europa Langmuir Probe (CELP) is a plasma instrument de- signed to characterize Europa’s plasma interaction to derive external magnetic fields. In order to accomplish the proposed science goal, CELP must be able to measure ion density, temperature, and flow direction. To do this, a design simi- lar to a cylindrical Faraday Cup is utilized, using three selection grids and four collecting surfaces. Necessary capabilities of the instrument include angular reconstruction in the yaw axis (theta) with respect to an ion beam, and in the roll axis (phi), both with picoamp current resolution. This study involved test- ing a prototype Ion Langmuir Probe using an ion beam in the lab. Data analysis shows angular resolutions of ±10° in theta and ±5° in phi [1] at ion tempera- tures of 400 eV and 900 eV, with currents on the order of 0.01 nA and 100 nA. The instrument must also show current resolution as low as the minimum ex- pected ionospheric currents at Europa of 10 pA/cm2 [2]. Using our experimental setup, current resolution at values as low as 0.1 pA/cm2 was observed. Along with achieving angular and current resolution goals, plots were produced that successfully match experimental data with analytical and simulation models, and the specified goals were achieved.