HR: 15:25h
AN: P52B-08    [PDF]
TI: Electrical Charging of the Aerosols in Titan's Atmosphere
AU: * Borucki, W J
EM: William.J.Borucki@nasa.gov
AF: NASA Ames Research Center, MS 244-30, Moffett Field, CA 94035-1000 United States
AU: Whitten, R C
EM: rwhitten@pacbell.net
AF: Raytheon STX Corp., NASA Ames Research Center MS 233-1, Moffett Field, CA 94035-1000 United States
AU: Bakes, E E
EM: bakes@shivakali.arc.nasa.gov
AF: SETI Institute, 2035 Landings Drive, Mountain View, CA 94043-0818 United States
AB: We have used recent data on graphitic cloud particles in the atmosphere or Titan to compute the electrical charging of the particles (radii ranging from 0.01 microns to 0.26 microns. The charging on the nightside was rather similar to that obtained earlier (Borucki et al, Icarus, 72, 604-622, 1987) except that charge distributions on the particles are now computed and recently obtained cloud particle sizes and density distributions were employed. The negative charge on particles of 0.26 microns peaked at 9 at 150 km altitude. The computations were repeated for the dayside with the addition of photoelectron emission by the particles as a result of the absorption of solar UV radiation. Particles (except the very smallest) now became positively charged with particles of radius 0.26 microns being charged up to +47. Next, very small particles (radii 0.0003 microns) of polycyclic aromatic hydrocarbons (PAHs) were introduced and treated as sources of negative ions since they could be either neutral or carry one negative charge. Moreover, they are mobile so that they had to be treated like molecular size negative ions although much more massive. They had the effect of substantially reducing the electron densities in the altitude range 190 to 310 km to values less than the negative PAH densities and increasing the peak electron charge on the larger particles. Particles of radius 0.26 microns bore peak charges of ~ +47 at altitudes of ~ 250 km. The simulated effect of PAHs on the nightside proved to be much less pronounced; at the peak negative PAH density, it was less than the electron density. The physics governing these results are discussed.
DE: 2419 Ion chemistry and composition (0335)
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2459 Planetary ionospheres (5435, 5729, 6026, 6027, 6028)
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting