HR: 1330h
AN: SM43C-04    [Abstracts]
TI: Comparisons of Thermal Electron Measurements on two Sounding Rocket Experiments
AU: * MacDonald, E
EM: elizabeth.macdonald@unh.edu
AF: University of New Hampshire, Space Science Center, Durham, NH 03824 United States
AU: Lynch, K
AF: Dartmouth College, Dept. of Physics and Astronomy, Hanover, NH 03755 United States
AU: Frederick-Frost, K
AF: Dartmouth College, Dept. of Physics and Astronomy, Hanover, NH 03755 United States
AU: Arnoldy, R
AF: University of New Hampshire, Space Science Center, Durham, NH 03824 United States
AU: Widholm, M
AF: University of New Hampshire, Space Science Center, Durham, NH 03824 United States
AU: Kintner, P
AF: Cornell University, Dept. of Electrical and Computer Engineering, Ithaca, NY 14850 United States
AU: Klatt, E
AF: Cornell University, Dept. of Electrical and Computer Engineering, Ithaca, NY 14850 United States
AU: Samara, M
AF: Dartmouth College, Dept. of Physics and Astronomy, Hanover, NH 03755 United States
AB: Thermal electron instruments built by the University of New Hampshire have accompanied standard instrumentation flown on a series of two sounding rocket flights, SIERRA and SERSIO. In 2002, SIERRA was launched from Poker Flat Research Range, Alaska, to 735 km into a modest substorm. The instrument response of the thermal electron detector (TED) has been studied extensively (MacDonald et al., 2004). The TED design featured a pinhole electrostatic analyzer designed to detect the flux and energy distribution of the coldest ambient ionospheric electrons. Despite positive biasing the instrument exhibited formation of a potential barrier restricting access to the thermal core. Using coincident data from other instruments information about the thermal plasma temperature, density, and spacecraft potential can be reconstructed. These data and the theories developed to examine them can be examined in conjunction with the next flight. In 2004, SERSIO was launched from Svalbard, Norway to 780 km in intense pre-storm cusp ion outflow. This payload contained two different designs for measuring thermal electrons and two identical but orthogonal top-hat thermal ion analyzers. In addition to the TED, another new instrument, the ERPA, was developed for detecting thermal electrons via an omni-directional retarding potential current collector. On the TED, the bias sweep and coating were altered to improve performance. Additionally the payload flew into sunlight whereas the previous flight was into total darkness which greatly changes the nature of the payload current balance situation. Unfortunately SERSIO data was severely limited by mechanical problems which affected instrument deployment and orientation but is still useful for this purpose. Extensive ground-based radar observations should prove useful for facilitating quantitative comparisons. The performances of the two TEDs are contrasted with the aim of identifying differences due to changes in internal instrumental parameters versus external environment parameters. Also, the two different thermal electron designs on SERSIO, the TED and the ERPA can be compared. Finally, this payload allows a complete comparison between ground-based thermal parameters and their in-situ electron and ion counterparts. This work should help us to understand more about the true nature of the potential sheath around a rocket, necessary for successful direct measurement of ionospheric thermal electrons.
DE: 2407 Auroral ionosphere (2704)
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2455 Particle precipitation
DE: 2467 Plasma temperature and density
DE: 2494 Instruments and techniques
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly