1. Toward a complete measurement of the thermodynamic state of an impact-induced vapor cloud S. Sugita, K. Hamano, T. Matsui University of Tokyo T. Kadono Institute for Earth’s Evolution (IFREE) P. H. Schultz Brown University

2. Importance of impact vaporization  Impact degassing (e.g., K/T)  Accretion of an atmosphere  Atmospheric erosion (e.g., Mars) However, physical state (e.g., EOS) and chemical reaction rates are highly uncertain.

3. The key is the thermodynamic state of resulting impact vapor clouds.  TemperatureT  Pressure P  Density   Entropys  Chemical compositionx  Ionization ratio  } Two of these four

4.  The thermodynamic state of an impact vapor cloud was difficult. Very high velocity launchers (>5km/s) Ultra-high speed detector (~10 -6 seconds) Diagnostic tools for temperature, pressure, and chemical composition

5.  The thermodynamic state of an impact vapor cloud was difficult. Not many facilities can achieve this velocity. Ultra-high speed detector (~10 -6 seconds) Diagnostic tools for temperature, pressure, and chemical composition

6.  The thermodynamic state of an impact vapor cloud was difficult. Not many facilities can achieve this velocity. Regular CCD is too slow (~10 -3 seconds). Diagnostic tools for temperature, pressure, and chemical composition

7.  The thermodynamic state of an impact vapor cloud was difficult. Not many facilities can achieve this velocity. Regular CCD is too slow (~10 -3 seconds). Regular thermometers, barometers, and chromatographs cannot be used.

8.  The thermodynamic state of an impact vapor cloud was difficult. Not many facilities can achieve this velocity. Regular CCD is too slow (~10 -3 seconds). Regular thermometers, barometers, and chromatographs cannot be used. è High-speed spectroscopy

9. Impact Flash Spectroscopy Pretty complex!

10. Impact Flash Spectroscopy High speed and high resolution are required.

11. Impact Flash Spectroscopy

12. Photonic emission from an atom

15. I l,m  h lm 4  A l,m g m Nexp  E m kT /Z (T) ( ) h, v, A, gZ(T)~1 where h, v, A, g are constant; Z(T)~1. ln ˆ I l,m  E m kT  lnN Emission intensity depends on both temperature and chemical composition. è where ˆ I l,m  I l,m A l,m g m h lm 4 

16. Boltzmann Diagram è Temperature T è Chemical composition x  Ionization ratio 

17. Thermodynamic state of impact vapor  TemperatureT a  Pressure P  Density   Entropys  Chemical compositionx a  Ionization ratio  a } Two of these four  Still not enough. We need one more!

18. Line width measurement  Spectral line width is controlled by: èDoppler broadening  Stark (Lorentz) broadening for H  (Griem, 1964)  c 2kT   6.3 x 10  16 n e 2/3 (nm)

19. Gypsum vapor in argon 100 - 200 ns Laser simulation: Nd:YAG, 10ns, 6x10 11 W/cm 2

20. Gypsum vapor in argon 400 - 500 ns Laser simulation: Nd:YAG, 10ns, 6x10 11 W/cm 2

21. Gypsum vapor in argon 4000 - 5000 ns Laser simulation: Nd:YAG, 10ns, 6x10 11 W/cm 2

22. Line width to pressure  n e = 6.3 x 10 22  1.5 (m -3 )   =  n e /N A (  = 1 is assumed.)  P =  RT ■ Saha’s equation or ion line intensity measurement should be used for an accurate estimate.

23. P-T diagram Slope:  = 1.3

24. Thermodynamic state of gypsum vapor  Enthalpy (H) and Gibbs free energy (G) can be also obtained. è  TemperatureT a  TemperatureT = 12,000 K a  Pressure P a  Pressure P = 0.1 bar a  Density  a  Density  =  1.7x10 -3 kg/m 3 a  Entropys a  Entropys = 10.5 kJ/K/kg a

25. Conclusion  Although still model dependent, we now have a method to measure the thermodynamic state of an impact-induced vapor cloud as a function of time and space.