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L. Habash Krause 1 , C. L. Enloe 1 , and F. A. Herrero 2

A Space-Based Instrument Suite to Characterize Small Scale Plasma Turbulence in the F Region Ionosphere. L. Habash Krause 1 , C. L. Enloe 1 , and F. A. Herrero 2 (1) United Stated Sir Force Academy, Department of Physics (2) NASA Goddard Space Flight Center. Presentation Overview.

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L. Habash Krause 1 , C. L. Enloe 1 , and F. A. Herrero 2

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  1. A Space-Based Instrument Suite to Characterize Small Scale Plasma Turbulence in the F Region Ionosphere L. Habash Krause1, C. L. Enloe1, and F. A. Herrero2 (1) United Stated Sir Force Academy, Department of Physics (2) NASA Goddard Space Flight Center

  2. Presentation Overview • Motivation: Support Ionospheric Radio Science Research • Plasma Local Anomalous Noise Environment (PLANE) Sensor • Flat Plasma Spectrometer (FLAPS) Sensor • FalconSAT-3 Mission FLAPS PLANE

  3. Experiment Motivation Scintillations disrupt signals important for communications/navigation systems. Unstable plasma within the Earth’s low latitude ionosphere results in irregularities in refractive index Scintillations occur when radio waves pass through a turbulent ionosphere, reducing signal quality

  4. 6 3 Log10 Ni (cm-3) -70° 0° 70° DMSP F-14 Data courtesy of Fred Rich (AFRL/VSBX) Magnetic Latitude Experiment Motivation Power in the noise approaches that of the signal for both VHF comm and L-band nav signals, especially in low latitudes Plasma bubbles most frequently observed near the magnetic equator

  5. Vertical Vertical Horizontal Horizontal Instability Mechanisms • Plasma depletions tend to form in the bottomside ionosphere, and if they upwell into the topside, they are called plasma bubbles. • Initial onset due to Rayleigh Taylor Instability Linear Development: Schematic (e.g., Chen) • Realistic description more complicated due to non-linear and kinetic effects. • Results from non-linear fluid treatment provide insight into bubble development the effects of plasma density gradient and collisions with the neutral atmosphere Non-Linear Development: Model Results (Hysell et al.)

  6. Maxwellian Fluid Non-Maxwellian Hybrid Simulations Plasma Simulations Plasma W W Rayleigh Rayleigh - - Taylor Simulations after Taylor Simulations after t = 40 t = 40 i i Instability Mechanisms • Simulations have shown that the Rayleigh Taylor Instability results in smaller-scale structures when plasma is treated as a massless electron/kinetic ion hybrid when compared to its fluid counterpart. • In situ measurements of ionospheric plasma spectra, differential in energy, provides information on the role of Non-Maxwellian plasma distributions on plasma bubble instigation/evolution. g Inertial Ion Length (c/wpi) Influence of kinetic effects on small scale structure (Winske)

  7. V In Situ Measurement of Ionospheric Plasma Turbulence: Challenges • Spacecraft-plasma interactions may perturb the environment local to the spacecraft • An accurate in situ measurement of the ambient environment cannot be made by a probe that disrupts the plasma in its vicinity. Quiescent? Turbulent? Space-borne plasma instruments can only see the local environment of the spacecraft. Spacecraft-induced turbulence can affect the plasma environment in the ram and wake.

  8. RPA 1 sees the entire plasma turbulent plasma at less than ram energy Compare noise signatures in different frequency bands. ambient plasma at the ram energy RPA 2 sees only the ambient plasma Results from the STS-60 mission indicate that a turbulent component of the plasma shares the motion of the spacecraft. Plasma Local Anomalous Noise Environment (PLANE) Objective:To identify/characterize turbulence in the plasma environment originating in the frame of reference of the spacecraft distinct from global variations. Description:The PLANE instrument will use a pair of planar retarding potential analyzers, linked by a feedback loop, to distinguish ambient ions from those co-moving with the spacecraft.

  9. PLANE ROCSAT-1 C/NOFS CHAWS DMSP 1 km 100 m 10 m 1 m 10 cm plasma feature scale size Plasma Local Anomalous Noise Environment (PLANE) • Mass-the mass of the RPA assembly: 0.2 kg. • PIB Mass- the mass of the PIB is 0.2 kg. • 1.5 W Average power • +5 V Nominal operating voltage • Discrete analog and digital I/O • Requires S/C management of operation.

  10. Flat Plasma Spectrometer (FLAPS) Advances in miniaturization technology have enabled significantly smaller plasma spectrometers FLAPS measures charged particle distributions differential in energy and angle. Initial concept shown here. FLAPS final configuration has five sensor heads, each with a unique look direction

  11. K.E. = 3.8 keV fd K.E. = 4.3 keV K.E. = 5.0 keV SIMION Trajectory Simulations Parallel Plate Analyzer and Analyzer Constant: Analyzer constant varies as (L/D)2. The analyzer constant P = 25 for the L/D = 10 shown here.

  12. FLAPS SIMION Model Results SIMION model runs used to investigate theoretical expression for plate factor for different plate geometries Plate factor P quantifies the ratio of charged particle voltage to plate voltage, related to plate geometry as: P= 6 Equation for P assumes uniform electric field At P=6, O+ passes through at 0.1825V. Theoretical voltage is 0.1667 V

  13. FLAPS Description Primary Objective • Assess relationship between non-thermalized plasma and small scale plasma bubbles Key Characteristics: • Ion Spectra, differential in energy and angle • 0.05 eV – 16 eV, 4% DE/E • 5 discrete angles (1 FOV each element) Physical Parameters (including electronics) • 5 Ion Spectrometers • Mass: ~ 400 g • Size: 9 cm  9 cm  7 cm • Mounting bracket: 10.5 cm outer edge • Internal microcontroller, EPROM, FPGA TLM Connection

  14. # # cm2-sec-Sr cm2-sec-Sr 21022 1022 1.51022 1020 11022 1018 O O N2 O2 0.51022 1016 Ar He N2 2.5 2.5 5 5 7.5 7.5 10 10 12.5 12.5 15 15 17.5 17.5 He O2 Ar Simulated Response k (eV) k (eV) Log Plot  Major and Minor Constituents Linear Plot  O, N2 The energy distribution at the peak of the angular distribution is simulated here for a realistic upper atmosphere.

  15. FalconSAT-3 Mission Overview • Mass: ~ 100 lb (~50 kg) • Size: 0.46 m (18 in) cube • Payloads: • Flat Plasma Spectrometer (FLAPS) • Plasma Local Anomalous Noise Environment (PLANE) • Micro Propulsion Attitude Control System (MPACS) • Orbit: • Altitude: 560 km • Inclination: 35 deg • Launch Vehicle: EELV/ESPA • Delivery: 3Q CY2006 • Launch: 4Q CY2006 • Operations: USAFA Ground Station

  16. Questions?

  17. Back-up Slides

  18. FLAPS Energy Selector SIMION 7.0 used to model charged particle trajectories in FLAPS energy selector • Modeling Objectives: • Verify instrument concept • Understand instrument response before functional testing • Determine transparency of instrument • Verify theoretical expression for plate factor

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