Electric field lab

Electric fields are a fundamental physical parameter in Nature. The Goddard E-field lab develops instrumentation that provide accurate measurements of both DC and AC vector electric fields which address critical research topics of Geospace and Space Weather. Specifically, the double probe technique (invented at Goddard in the 1960's) is a successful, proven, straightforward technique to measure both DC and AC vector electric fields. The data collected from multiple missions using these techniques lends itself well for analysis and interpretation, including both detailed case studies and cumulative "big picture" studies. Goddard's Electric field experimental research is at the core of NASA's fundamental strategic goals and is one of the oldest, continuously operating labs at NASA (since the mid- 1960's). We are Tier-2 instrument, providing recognized expertise for the NASA and heliophysics community. Electric Field double probes provide DC and AC electric fields, interferometers, HF vector -- all of which we embrace as a science team. Our work includes hardware (booms, electronics including on-board processing and burst memory) and data analysis and interpretation, publication. We are a edicated team of about 10 persons including many who have been with the group for over 20 years. The E-field lab takes pride in the missions and work as well as the training of the next generation through the numerous interns, studnets, and postdocs which have worked with the lab throughout the years.

Scientific Goals and Motivation

Discover and investigate to better understand electric fields in nature.

Electric fields address fundamental physics and are critical to understand plasma motions, energy and momentum transfer, Particle acceleration, and turbulence. Below are some of the topics the E-field lab focuses on

DC Electric Fields/Quasi-Steady -- Magnetospheric driven Convection electric fields move plasma via electric and magnetic field drifts; Ionospheric polarization fields sustained by winds, conductivity gradients, gravity waves, etc.

DC-Coupled Electric Fields/Structured -- Shocks/Parallel electric fields associated with particle acceleration, MHD breakdown; Time Domain Structures in magnetosphere; Structured Electric fields and irregularities; Electric fields in dusty plasmas, noctilucent clouds; Thunderstorms and lightning-related electric fields

AC Electric Fields -- Plasma waves (electrostatic and electromagnetic) Accelerate particles, redistribute energy, remote of environment of earth, other planets; Generate intense planetary radio emissions

Magnetosphere-Ionosphere coupling -- E-fields are also a remote sensing technique often used to infer dynamics of the ionosphere and magnetosphere.

Instrumentation

Electric field double probes -- DC and AC electric fields (Pioneered at Goddard in the 1960's!)

Vector measurements on non-spinning satellites in the ionosphere is our speciality. Electric field double probes lends itself well to planetary missions as well as sounding rockets addressing science topics at low, mid, and high latitudes, DC and AC electric fields, interferometers, HF vector.

Booms for:

satellites: wire booms and stiff booms

rockets: Inexpensive fold-down booms with double spheres; accommodates other instruments such as search coils Developing precise ways to measure very small variations of boom deflections from which neutral density and winds

Flexibility and scalability of electric field experiment (e.g., booms) tailored to meet individual science objectives Small sphere payload with vector electric field double probes for mesosphere and lower thermosphere research

Cube-sat electronics developed and flown on a rocket (fits inside a 1-U volume.) State-of-the-art electronics with on-board processing and burst memory (included in our experiment on C/NOFS.)

Our team also designs/builds plasma density instruments:

Langmuir probes (fixed-bias and swept)

Impedance probes

Data Analysis

The Electric field lab has been included with many projects including EXB drifts, polarization electric fields, AC plasma waves (ULF - HF), and plasma irregularities. The lab is active in the callibration and validation of accurate DC electric fields using vector measurements on non-spinning platforms (e.g. C/NOFS, and DE-2 satellites). They have also develoed data sets for major models of high latitude plasma convection (e.g., Weimer model). Additionally they have developed multiple-baseline interferomety and derivations of plasma densty from plasma wave cut-offs.

Projects

Past Satellites:

DE-2,

San Marco,

C/NOFS,

CRESS,

OGO-6,

ISEE-1,

SCATHA

Funded projects

analisis of DE-2 and C/NOFS data

data production and archival of DE-2 and C/NOFS data

The lab also continues analysis of FAST, Polar, Cluster electric field data

Have designed and flown electric field experiments on over 75 sounding rockets including those at high, mid, and low latitudes.

Satellite Proposals

Experiments, both satellites and rockets, are part of extensive instrumentation designed to answer key science questions -- Hence, E-fields experiments are carried out in conjunction with magnetometers, particle instruments, neutral gas measurements including winds, plasma density, optical lightning detectors, etc.

Examples of rocket experiments have focused on (100 - 1000km):

Dynamo, Electrojet, Collisional dynamics

Creation of associated with the aurora

in the sunset ionosphere at the equator

Irregularities and plasma instabilities -- Kelvin-Helmholtz instability associated with sporadic-E wind shear, two-stream instabilities in the auroral and equatorial electrojets, Spread-F, etc.

Active Experiments (APEX, KiNETX, BeamPIE) including high speed ion releases and electron beams

Powerline emissions, transmitters, Schumann Resonances (discovered in space with Goddard double probes!)

Derive plasma density from plasma wave cutoffs measured by electric field AC experiments

Typical GSFC Electric Field Experiments include:

DC and AC electric fields, interferometers, HF vector fields;

DC magnetometers (flux gate) from either Code 695 or procured from industry

Langmuir probes (swept and fixed-bias) Vortexplasma Plasma density, temperature, s/c potential

Impedance probes Jetsneutral absolute plasma density; info on collisions

Collaborate with other groups both at Goddard and external

The E-field team collaborates with many groups both within and outside of Goddard. This allows for us to build fully integrated team: Science + analysis. We have many well-maintained collaborations: Code 690 (Planetary science division at NASA Goddard), UNH, UCB and many of our experiments are carried out in conjunction with ground-based observations (e.g., radars, ionosondes).