NSSL EFM Instrument
The Electric Field Mapper (EFM) is a balloon-borne instrument developed by the
National Severe Storms Laboratory (NSSL) to measure the vector electric field in the
atmosphere during flight. It is designed to operate in severe weather conditions and
collect high-resolution data on electric field structure, environmental parameters, and
instrument dynamics.
The EFM consists of multiple integrated subsystems, including rotating sensor spheres,
precision charge amplifiers, GPS tracking, orientation sensing, and onboard data
logging. Rotating electronics handle data collection from key sensors, including charge
transfer, GPS, temperature, pressure, and humidity. Motor control electronics regulate
rotation rate and monitor system health, while an IMU-based orientation paddle tracks
the instrument’s motion throughout flight.
A satellite-based tracker provides real-time GPS updates for monitoring and recovery.
Mechanical components—ranging from 3D-printed mounts to machined parts and
lightweight foams—support and protect the system under demanding conditions.
This documentation site includes user guides, design files, firmware references, and
mechanical documentation to support continued development, deployment, and analysis
of the EFM system.