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New ELF/VLF Wave Injection Facility

New ELF/VLF Wave Injection Facility. Motivation: increased scientific interest in wave-particle interactions and their global role in the acceleration and loss of energetic particles

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New ELF/VLF Wave Injection Facility

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  1. New ELF/VLF Wave Injection Facility • Motivation: increased scientific interest in wave-particle interactions and their global role in the acceleration and loss of energetic particles • Active experiments allow us to quantify these complex non-linear interactions in way that passive observations or numerical modeling do not. • New facility would be open for experiments to be conducted by independent investigators • Suites of supporting instrumentation at the site, in the conjugate region, and arrays of low-power instruments at distances away from the site

  2. Siple Station, 1973-1989

  3. Electron Precipitation • Clear evidence of electron precipitation induced by Siple was not found. • Siple frequencies were likely too high • Detection instruments were not as developed • inside plasmapause, 3-5 kHz waves resonate with few keV electrons • Radiating at lower frequencies would be a major improvement • inside plasmapause, 500 Hz waves resonate with 10’s of keV electrons Dots are measured duct parameters from Siple

  4. Observing Precipitation • Significant advances in instrumentation increase the ability to measure low levels of electron precipitation • Optical instruments, photometers and imagers • Imaging riometers • Subionospheric VLF remote sensing • X-rays • Ground based / Balloon / Rocket / Spacecraft

  5. ULF/VLF Interactions The transmission format at Siple was limited The new facility would investigate the generation of ULF waves by amplitude modulated transmission at VLF frequencies. • Generate ULF micropulsations (0.1 sec to 10 min period) • Detect with arrays of LPM [Bell, 1976]

  6. Facility Location • > 2000 m ice thickness • Proximity to the plasmapause, L=4-5 • Easy access to the northern hemisphere conjugate region • Excitation of wave-particle interactions involving > 40 keV electrons (freq as low as 500 Hz) • Effective radiated power of 10-50 kW

  7. Ice Thickness Ice thickness is critical in determining radiation efficiency Siple

  8. 1989 Workshop & Report

  9. 1989 Workshop & Report

  10. 1989 Workshop & Report

  11. Antenna Configurations For operation at 500 Hz, l = 200 km

  12. Siple Station, Antarctica VLF Wave-injection Experiment • NSF-funded Stanford experiment (1973-88) • VLF waves (~2-6 kHz) injected from Siple Station, Antarctica • 150 kW transmitter, 42-km antennas • Tuned with large capacitors and coils • VLF receiver at Roberval & Lake Mistissini, Quebec • Controlled studies of cyclotron resonant wave-particle interactions • Uncovered many aspects of wave growth & emission triggering

  13. Amplified VLF Signals with Intense Triggered Emissions

  14. Modification of the Electron Distribution?

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