Ionosphere

In this section, the wide diversity of teclmiques used to explore ion chemistry and ion structure will be outlined and a sampling of the applications of ion chemistry will be given in studies of lamps, lasers, plasma processing, ionospheres and interstellar clouds. 

Above approximately 80 km, the prominent bulge in electron concentration is called the ionosphere. In this region ions are created from UV photoionization of the major constituents—O, NO, N2 and O2. The ionosphere has a profound effect on radio conmumications since electrons reflect radio waves with the same frequency as the plasma frequency, f = 8.98 x where 11 is the electron density in [147]. The... 

Ferguson E E, Fehsenfeld F C, Dunkin D B, Schmeltekopf A L and Schiff FI I 1964 Laboratory studies of helium ion loss processes of interest in the ionosphere Planet Space Scl. 12 1169-71... 

Mass spectrometric investigations of the ionosphere show an abundance of molecular ions such as NO and watercluster ions [4T ]. This is an indication of the result of ion-molecule reactions which change the chemical state of the ions in this plasma ... 

Molecular ions have an important role in charge carrier losses in the ionosphere. The probability of electron-atom-... 

The ozone fonnation in the atmosphere is induced by radiation and a result of tliree-body collisions of the oxygen atoms with O2 molecules. This process requires a higher gas density and is, therefore, not efficient in the ionosphere. 

Kelley M C 1989 The Earth s Ionosphere Plasma Physics and Electrodynamics (San Diego, CA Academic)... 

Bauer S J 1973 Physics of Planetary Ionospheres (Berlin Springer)... 

Plasma Types. Eigure 1 (7—9) indicates the various types of plasmas according to their electron density and electron temperature. The colder or low electron energy regions contain cold plasmas such as interstellar and interplanetary space the earth s ionosphere, of which the aurora boreaUs would be a visible type alkaU-vapor plasmas some flames and condensed-state plasmas, including semiconductors (qv). 

Fig. 5. Ionospheric electron density vs height above the earth at the extremes (A = minimum, B = maximum) of the 11-yr sunspot cycle during (a) day and (b) night (54). D, E, F, F, and F2 are conventional labels for the indicated regions of the ionosphere.

The ionosphere is part of the larger magnetosphere, a cavity in the stream of particles from the sun. The cavity is produced by the earth s magnetic field (56,57). The ionosphere and the Van AHen radiation belt He within the plasmasphere, which extends to a maximum distance of about 15,000 km above the earth s surface. 

The ionosphere is subject to sudden changes resulting from solar activity, particularly from solar emptions or flares that are accompanied by intense x-ray emission. The absorption of the x-rays increases the electron density in the D and E layers, so that absorption of radio waves intended for E-layer reflection increases. In this manner, solar flares dismpt long-range, ionospheric bounce communications. 

Earth to space (sateUite) to earth communication links are relatively insensitive to ionospheric disturbances. Communications between earth and manned space vehicles are barely affected by plasmas when the spaceships are well away from the atmosphere, eg, in orbit or in a translunar trajectory. However, during reentry of a spaceship, a low temperature plasma forms around the vehicle and intermpts the communication links to it (183). Plasmas are incidental to the performance of modem rockets used to explore the solar system. 

H. Risbeth and O. K. Gardot, Introduction to Ionospheric Physics, Academic Press, Inc., New York, 1969. 

On a macroscale (Fig. 2-1) as temperature varies with altitude, so does density (1). In general, the air grows progressively less dense as we move upward from the troposphere through the stratosphere and the chemo-sphere to the ionosphere. In the upper reaches of the ionosphere, the gaseous molecules are few and far between as compared with the troposphere. 

The ionosphere and chemosphere are of interest to space scientists because they must be traversed by space vehicles en route to or from the... 

The cross-section for the reaction, 0 + + N2 -+ NO+ + N, as a function of the ion energy, has a maximum of about 4 X 10 u sq. cm. at 10 e.v. and falls off for higher or lower ion energies. The low energy fall-off of the cross-section explains the persistence of 0 + ions in the ionosphere but is a puzzling and unexpected result. Some very tentative reasons for this fall-off are suggested. 

Earlier measurements using a variety of techniques are summarized by Paulson (19) and Ferguson et al. (6). There seems to be no doubt now about the fall-off of the cross-section at low energies. This window for low energy O + ions explains their persistance in the ionosphere, but it remains a theoretical puzzle. 

Henry Rishbexh and Owen K. Garriott. Introduction to Ionospheric Physics. 1969 ... 

Peter Warneck. Chemistry of the Natural Atmosphere. 1988 S. Pal Arya. Introduction to Micrometeorology. 1988 Michael C. Kelley. The Earth s Ionosphere. 1989 William R. Cotton and Richard A. Anthes. Storm and Cloud Dynamics. 1989... 

Yamazaki H, Yamaguchi T, Yamaguchi A, et al. 1992. Effect of halocarbons and styrene on thrombin and calcium ionosphere induced activation of rabbit platelets. Chemosphere 25 665-673. 

Figure 12.3.1 A rare high-altitude red aurora created in the ionosphere. Photo by Ja Curtis, courtesy of The Exploratorium.

The layers of sediment at the Martian south pole do not consist of pure ice they are interspersed by layers of dust. The latest data were obtained by the Mars Advanced Radar for Subsurface and Ionospheric Sounding apparatus (MARSIS) on board the Mars Express Orbiter. The radar waves from the instrument pass through the ice layers until they reach the base layer, which can be at a depth of up to 3.7 km. The distribution of the ice at the south pole is asymmetric, and its total volume has been estimated to be 1.6 x 106km3 this corresponds to an amount of water which would cover the whole planet with a layer 11 metres deep (Plaut et al., 2007). 

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