HOT PLASMA PARAMETERS OF JUPITER INNER MAGNETOSPHERE

The bulk parameters of the hot (>20 keV) plasmas of Jupiter's inner ma gnetosphere, including the vicinity of the Io plasma torus, are presen ted for the first time (L = 5 to 20 R(J)). The low-energy charged part icle (LECP) instrument on Voyager 1 that obtained the data presented h ere was severely overdriven within the inner regions of Jupiter's magn etosphere. On the basis of laboratory calibrations using a flight spar e instrument, a Monte Carlo computer algorithm has been constructed th at simulates the response of the LECP instrument to very high particle intensities. This algorithm has allowed for the extraction of the hot plasma parameters in the Jovian regions of interest. The hot plasma c omponents discussed here dominate over other components with respect t o such high-order moments as the plasma pressures and energy intensiti es. Our findings include the following items. (1) Radial pressure grad ients change from positive (antiplanetward) to negative as one moves o utward past about 7.3 R(J). While the observed hot plasma distribution s will impede the radial transport, via centrifugal interchange, of io genic plasmas throughout the Io plasma torus regions out to 8 R(J), th e plasma impoundment concept of Siscoe et al. [1981] for explaining th e so-called ''ramp'' in the flux shell content profile of iogenic plas mas (7.4-7.8 R(J) [Bagenal, 1994]) is not supported. (2) We predict a radical ordering for the generation of the aurora, which translates in to a latitudinal structure for auroral emissions. Planetward of about 12 R(J), intense aurora (10 ergs/(cm(2) s) precipitation) can only be caused by electron precipitation, whereas outside of about 12 R(J) suc h intense aurora can only be caused by electron precipitation. Uncerta inties concerning the causes of Jovian aurora may stem in part from fa ilures of some observations to resolve the latitudinal structure that is anticipated here and possibly from changes in the aurora; configura tion and/or charged particle spectral properties since the Voyager epo ch.