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Ann. Geophys., 23, 2825-2849, 2005
www.ann-geophys.net/23/2825/2005/
© European Geosciences Union 2005
The NUADU experiment on TC-2 and the first Energetic Neutral Atom (ENA) images recorded by this instrument
S. McKenna-Lawlor1, L. Li2, S. Barabash3, K. Kudela4, J. Balaz1, I. Strharsky1, K. Brinkfeldt3, H. Gunell1,3, C. Shen2, J. Shi2, J.-B. Cao2, Q. Zong2, S-Y. Fu5, E. C. Roelof6, P. C. Brandt6, and I. Dandouras7
1Space Technology Ireland, National University of Ireland, Maynooth, Co. Kildare, Ireland
2Centre for Space Science and Applied Research of the Chinese Academy of Sciences, Beijing, China
3Swedish Institute of Space Physics, Kiruna, Sweden
4Institute of Experimental Physics, Kosice, Slovakia
5School of Earth and Space Sciences, Peking University, Beijing, China
6The Johns Hopkins University, Applied Physics Laboratory, Laurel, Maryland, USA
7Centre d’Etude Spatiale des Rayonnements, Toulouse, France
Abstract. The spacecraft potential of Double Star TC-1 is positive in large parts
of the orbits due to the photo-effect from solar EUV irradiation. These
positive potentials typically disturb low energy plasma measurements on
board. The potential can be reduced, and thereby the particle measurements
improved, by emitting a positive ion beam. This method has successfully been
applied on several other spacecraft and it has also been chosen for TC-1.
The instrument TC-1/ASPOC is a derivative of the Cluster/ASPOC
instruments, from which it has inherited many features. The paper describes
the adaptations and further developments made for the ion emitters and the
electronics. The instrument performs very well and can support higher beam
currents than on Cluster. The expected significant improvement of the low
energy particle measurements on board was indeed observed. The modifications
of the electron distributions are analysed for a one-time interval when the
spacecraft was located in the magnetosheath. The change in the potential due
to the ion beam was determined, and first studies of the 3-D electron
distributions in response to the spacecraft potential control have been
performed, which indicate that the method works as expected.
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