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999999-1 XYZ 5/4/2015 MIT Lincoln Laboratory Sprite Light in a Bottle URSI Meeting Boulder, CO January 5, 2004 Earle Williams, MIT, Cambridge, MA Michael.

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Presentation on theme: "999999-1 XYZ 5/4/2015 MIT Lincoln Laboratory Sprite Light in a Bottle URSI Meeting Boulder, CO January 5, 2004 Earle Williams, MIT, Cambridge, MA Michael."— Presentation transcript:

1 XYZ 5/4/2015 MIT Lincoln Laboratory Sprite Light in a Bottle URSI Meeting Boulder, CO January 5, 2004 Earle Williams, MIT, Cambridge, MA Michael Valente, East Coast Induction, Brockton, MA Robert Golka, Golka Associates, Brockton, MA

2 MIT Lincoln Laboratory XYZ 5/4/2015 A Small Tube

3 MIT Lincoln Laboratory XYZ 5/4/2015 Current Density in Glow Discharge Tubes Investigator Current Density J (Amperes/m 2 ) DC Current Herz (1895) 2-15 Wilson (1902) Townsend (1915) 3 Günther-Schulze (1924) 4.2 Günther-Schulze (1927) Found and Langmuir (1931) 1.5 Capacitive Discharge Naudé (1932) 1-2 x 10 4 Elmore (1974) 7 x 10 4 Goto et al (2003) 8 x 10 3 This study.004 to 40

4 MIT Lincoln Laboratory XYZ 5/4/2015 The Large Discharge Tube

5 MIT Lincoln Laboratory XYZ 5/4/2015 Replacement of Lower Electrode

6 MIT Lincoln Laboratory XYZ 5/4/2015 Air Pressure vs. Altitude

7 MIT Lincoln Laboratory XYZ 5/4/2015 Absolute Spectral Units PR-650 Colorimeter provides spectral radiance L in absolute units (watts/m 2 /sr/nm) Rayleighs (megaphotons/cm 2 /sec) = 4  (sr/unit sphere) BW (nm) L (watts/m 2 /sr/nm) hc/ (joule/photon) (10 4 cm 2 /m 2 )(10 6 photons/megaphoton) = (2.39 x ) L

8 MIT Lincoln Laboratory XYZ 5/4/2015 Spectral Comparison

9 MIT Lincoln Laboratory XYZ 5/4/2015 Radiance vs. Input Power

10 MIT Lincoln Laboratory XYZ 5/4/2015 Striations in Positive Column (P = 70 mT) (J = 0.12 A/m 2 )

11 MIT Lincoln Laboratory XYZ 5/4/2015 Constricted Discharge at Higher Pressure (1.2 TORR) (6.6 A/m 2 )

12 MIT Lincoln Laboratory XYZ 5/4/2015 Radiance vs. Current Density

13 MIT Lincoln Laboratory XYZ 5/4/2015 Conductivity vs. Radiance

14 MIT Lincoln Laboratory XYZ 5/4/2015 Column Sprites J (A/m 2 ) A/m 2 3 x A/m A/m 2 Elizabeth Gerken

15 MIT Lincoln Laboratory XYZ 5/4/2015 Carrot Sprite Elizabeth Gerken J (A/m 2 ) A/m 2 3 x A/m A/m 2

16 MIT Lincoln Laboratory XYZ 5/4/2015 Large and Energetic Sprite Elizabeth Gerken

17 MIT Lincoln Laboratory XYZ 5/4/2015 Sub-Structure of Sprite Elizabeth Gerken J (A/m 2 ) A/m 2 3 x A/m A/m 2

18 MIT Lincoln Laboratory XYZ 5/4/2015 Langmuir’s Plasma Frequency

19 MIT Lincoln Laboratory XYZ 5/4/2015 Conclusions Sprite spectra are reasonably well replicated in an air-filled glow discharge tube, with dominant N 2 1PG emission (red light) The power dissipation per unit volume for a 1 Megarayleigh sprite is inferred to be ~1 watt/m 3 The current density in a 1 Megarayleigh sprite streamer is inferred to be ~10 -2 A/m 2, with radiance proportional to current density The electrical conductivity of a 1 Megarayleigh sprite at km altitude is inferred to be ~3 x mho/m, with conductivity proportional to radiance


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