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**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 1 1

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A Small Tube

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**Current Density in Glow Discharge Tubes**

Investigator Current Density J (Amperes/m2) DC Current Herz (1895) Wilson (1902) Townsend (1915) Günther-Schulze (1924) Günther-Schulze (1927) Found and Langmuir (1931) Capacitive Discharge Naudé (1932) x 104 Elmore (1974) x 104 Goto et al (2003) x 103 This study to 40

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**The Large Discharge Tube**

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**Replacement of Lower Electrode**

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**Air Pressure vs. Altitude**

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**Absolute Spectral Units**

PR-650 Colorimeter provides spectral radiance L in absolute units (watts/m2/sr/nm) Rayleighs (megaphotons/cm2/sec) = 4 (sr/unit sphere) BW (nm) L(watts/m2/sr/nm) hc/ (joule/photon) (104 cm2/m2)(106photons/megaphoton) = (2.39 x 1011) L

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Spectral Comparison

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**Radiance vs. Input Power**

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**Striations in Positive Column**

(P = 70 mT) (J = 0.12 A/m2)

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**Constricted Discharge at Higher Pressure**

(1.2 TORR) (6.6 A/m2)

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**Radiance vs. Current Density**

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**Conductivity vs. Radiance**

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**Column Sprites J (A/m2) 10-2 A/m2 3 x 10-3 A/m2 10-3 A/m2**

Elizabeth Gerken

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**Carrot Sprite J (A/m2) 10-2 A/m2 3 x 10-3 A/m2 10-3 A/m2**

Elizabeth Gerken

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**Large and Energetic Sprite**

Elizabeth Gerken

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**Sub-Structure of Sprite**

J (A/m2) 10-2 A/m2 3 x 10-3 A/m2 10-3 A/m2 Elizabeth Gerken

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**Langmuir’s Plasma Frequency**

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Conclusions Sprite spectra are reasonably well replicated in an air-filled glow discharge tube, with dominant N21PG emission (red light) The power dissipation per unit volume for a 1 Megarayleigh sprite is inferred to be ~1 watt/m3 The current density in a 1 Megarayleigh sprite streamer is inferred to be ~10-2 A/m2, with radiance proportional to current density The electrical conductivity of a 1 Megarayleigh sprite at km altitude is inferred to be ~3 x 10-5 mho/m, with conductivity proportional to radiance

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