Ionization from Solar Pumped Metastable Levels of Atomic Samarium - PowerPoint PPT Presentation

Ionization from Solar Pumped Metastable Levels of Atomic Samarium Paul A Bernhardt 1 , Carl L Siefring 1 , Albert Viggiano 2 , Jeffrey M. Holmes 2 Todd R. Pedersen 2 , Ron Caton 2 , Daniel Miller 2 and Keith M Groves 3 (1)Naval Research Laboratory, Washington, DC (2)Air Force Research Laboratory, Kirtland AFB, NM (3) Inst. Sci. Res., Boston College, Chestnut Hill, MA Work Sponsored at NRL by 6.1 Base Program

AFRL MOSC Experiment ( Radar Data from ALTAIR) ALTAIR – Incoherent Scatter Radar ALTAIR Raster Scans Altitude-vs-Time Click for Time of Rocket ALTAIR Release Pointing in beam Resulting Movie MOSC Layer ALTAIR Scan Altitude-vs-Ground Distance Spatial view of MOSC cloud ~40 minutes after release Ionospheric Density Ionospheric Density Profile prior to release Profile with MOSC Layer CLOUD MUCH LESS DENSE THAN PREDICTED BUT DISTRIBUTION STATEMENT B: Distribution authorized to U.S. Government agencies only; Administrative or DID HAVE SIGNIFICANT IMPACT ON IONOSPHERE Operational Use; 07 Oct 2013. Other requests for this document shall be referred to Air Force Research Laboratory/(office symbol), 3550 Aberdeen Ave SE, Kirtland AFB, NM 87117-5776. 2

Ionization Processes in Samarium Vapor • Why did MOSC Samarium Not Produce Predicted Density Levels? • Samarium Atom Photo Chemistry (NRL CRM) – Sm Energy Levels – Sm Metastable Level Pumping in Sunlight (Important) – Samarium Photo-Ionization (Important but Slow) – Samarium Associative Ionization with Atomic Oxygen • Reaction Energy – Weakly Exothermic from Ground State Sm (7F) Metastable Levels – Strongly Exothermic from Higher Sm(9H, 7H, …) Metastable States • SmO + Production (Autoionization) and Loss (Recombination-Important) – Samarium Reaction with Diatomic Oxygen (Important) • 3-D Time Dependent Predictions for MOSC Release • Data Acquired During AFRL MOSC Experiment for Comparison – Initial Electron Production Inventory from NRL CERTO Beacon – Altair Radar Map of Electron Density – AFRL Spectrogram of Optical Emissions • Conclusions

Conceptual Samarium Photo Chemistry Ions e - Sm(X 7 F) O SmO + Solar Resonance Fluorescence h ν h ν Solar Photo-Ionization Auto-Ionization with Atomic Oxygen O Dissociative Recombination e - Oxidation with Molecular Oxygen O 2

Samarium Photo Chemistry . . . Sm + Emissions Sm Emissions . . . . . . e - h ν h ν h ν Sm( 7 G o ) Sm(B 9 D) Sm +( 8G o) Sm + O Odd Level Sm Ions Excited Sm + Metastable Sm SmO Emissions h ν h ν h ν e - h ν Sm( 9 D o ) Sm(A 9 H) O SmO + h ν O 2 h ν h ν h ν O 2 h ν h ν O e - O h ν h ν Sm( 9 G o ) Sm(X 7 F) O 2 SmO* SmO Vibronic SmO Solar Resonance Fluorescence h ν h ν Solar Photo-Ionization Auto-Ionization with Atomic Oxygen O Dissociative Recombination e - Oxidation with Molecular Oxygen O 2

All Known Samarium Atomic Levels Sm + 8F0 γ B αγ A γβ α k γ αβ β Permitted Transitions Forbidden Odd Levels Transition Even Levels

Normalized Equilibrium Populations of the Metastable Levels of Samarium with Direct Solar Illumination with Auto-Ionization Dependence on Energy Slow Auto-Ionization Fast Auto-Ionization

Samarium Neutral Diffusion Based on the MSIS Atmosphere for 9 May 2013 -1 1/2   1/2     3 m 8 kT ∑ = = +     Sm  Sm  D 1/ D where D 1 and j = O, N , or O   π Sm Smj Smj 2 2 2     32 fr n m m   ≠ j Sm Smj j j Sm D Sm = 5.83 x 10 8 cm 2 /s at 171 km Altitude

(Latest) Time Dependent Computation of Sm + and SmO + Ions for Sm Release in Sunlight and Autoionization Reaction with O • Solar Photoionization Reaction β + − − − + ν  → + β = τ = = 1 1 Sm h Sm e rate: 0.00442 s , k 220 s SmSun Sun SmSun SmSun SmSun Metastable State Autoionization Reaction for Release at 171 km Altitude • + − +  → + + ∆ = φ σ k + Sm * O SmO e E rate: k v Sm O α + + Sm O SmExo Sm O φ = σ × − = 15 2 ฀ ฀ ฀ 0.104, 5 10 cm , v kT / m 718 m/s for T 1000 K + SmExo Sm O O O O × − = × β = = 10 3 9 -3 -1 ฀ 3.73 10 cm /s, 6.8 10 cm , 2.54 s k n k n + + + Sm O O Sm O Sm O O α +  k → + Samarium Oxidation* • Sm+O2 Sm [ ] O SmO O 2 − × = × β = = 10 3 8 -3 -1 ฀ k 5.1 10 cm /s, n 6.4 10 cm , k n 0.32 s + + + Sm O O Sm O Sm O O 2 2 2 2 2 • Dissociative Recombination Reaction + − k − − Γ +  → + ≈ + − 6 7 3 7 3 1 SmO [ ] e Sm F [ ] O P [ ] rate: k 10 cm s SmO e + − SmO e *Note: Sm + O 2 Reaction from M. L. Campbell, Temperature-Dependent Rate Constants for the Reactions of Gas-Phase Lanthanides with O 2 , J. Phys. Chem. A, 1999, 103 (36), pp 7274–7279

3D Numerical Model of Sm Release Photochemistry • Neutral and Ion Equations with Chemical Reactions – Neutral Samarium, Samarium Monoxide Ion, Samarium Ion, Samarium Monoxide, Electrons ∂ ∂  ∂ ∂  2 N D N N = + − β + Sm 1 Sm Sm  R  D N k N N + − + ∂ ∂ ∂ 1 Sm Sm e   2 SmO e SmO dt R R R z ∂ ∂ 2 N N + + = + β − β = SmO SmO D N k N N , k n + + + + − + ∂ 1 Sm O Sm e Sm O Sm O O 2 S mO e SmO dt z ∂ ∂ 2 N N + + = + β Sm S m D N ∂ 1 SmSun Sm 2 d t z ∂ ∂  ∂ ∂  2 N D N N = + + β β = SmO 1 S mO SmO  R  D N , k n + + + ∂ ∂ ∂ 1 Sm O Sm S m O Sm O O   2 dt R R R z 2 2 2 2 = + β ≡ β + β + β , N N N + + + + e Sm SmSun Sm O Sm O Sm Sm O 2 • Cylindrical Coordinates with z along B • Numerical Solution by Expanding Boundary Coordinate Transform

Central Cloud Density for Samarium Release with No Recombination Sm Release Product Neutrals and Ions 10 7 e ฀ SmO ฀ Many Electrons 10 6 3 ฀ cm ฀ SmO Density ฀ 10 5 10 4 Sm ฀ Time ฀ Seconds ฀ 1000 Sm 0 100 200 300 400 500 600

Central Cloud Density for Samarium Release Including Recombination Sm Release Product Neutrals and Ions 10 7 Much Less Electrons More SmO 3 ฀ 10 6 SmO cm ฀ Density ฀ e ฀ SmO ฀ 10 5 Sm ฀ 10 4 Time ฀ Seconds ฀ Sm 0 100 200 300 400 500 600

New 3-D Model for Samarium Release at t = 20 s Maximum Sm Density: Maximum SmO Density: 1.0 10 6 cm -3 4.2 10 7 cm -3 Maximum Sm + Density: Maximum SmO + Density: Maximum Electron Density: 1.6 10 6 cm -3 2.6 10 6 cm -3 1.0 10 6 cm -3

3-D Model for Samarium Release at t = 100 s Maximum Sm Density: Maximum SmO Density: 3.9 10 3 cm -3 3.7 10 6 cm -3 Maximum Sm + Density: Maximum SmO + Density: Maximum Electron Density: 4.4 10 4 cm -3 4.7 10 5 cm -3 4.2 10 5 cm -3

Resonance Fluorescence of Samarium Atoms and Atomic Ions γ ν h αγ ν h γβ B αγ A γβ α Sm k γ αβ β SmO? π = 4 I (Rayleighs) γ β Sm ∫ − ε 10 0 1 N ( ) s d s γβ Sm S m + π = 4 I ( Sm ,Rayleighs) + γβ Sm ∫ − ε 10 1 0 N ( s ) ds + + γ β S m Sm Sm + Sm +

Estimated Total Electron Content Yield for MOSC Samarium Releases MOSC CERTO Beacon to Rongelap, 1 and 9 May 2013 MOSC 2 Rocket to Ground TEC (10 16 m -2 ) 5.2 TEC Units MOSC1 3.4 TEC Units (Only One Canister?) Beacon Path Moves Out of Decaying Cloud Flight Time (s)

AFRL MOSC Experiment, ALTAIR – Launch 2 DISTRIBUTION STATEMENT B: Distribution authorized to U.S. Government agencies only; Administrative or Operational Use; 07 Oct 2013. Other requests for this document shall be referred to Air Force Research Laboratory/(office symbol), 3550 Aberdeen Ave SE, Kirtland AFB, NM 87117-5776.

Central Cloud Density for Samarium Release Including Recombination Sm Release Product Neutrals and Ions 10 7 Measured with ALTAIR 3 ฀ 10 6 SmO cm ฀ Density ฀ e ฀ SmO ฀ 10 5 Sm ฀ 10 4 Time ฀ Seconds ฀ Sm 0 100 200 300 400 500 600

MOSC Optical Spectra (From Todd Pedersen and Jeff Holmes, AFRL) Sm* Enhanced Emissions Above Background 8 Seconds After MOSC Release on 9 May 2013 Blue Enhanced Emissions 68 Seconds After MOSC Release Blue Red Sm + * SmO*