Triton: Topside ionosphere and nitrogen escape



The principal ion in the ionosphere of Triton is N+. Energetic electrons of magnetospheric origin are the primary source of ionization, with a smaller contribution due to photoionization. To explain the topside plasma scale height, we postulate that N+ ions escape from Triton. The loss rate is 3.4 × 107 cm−2 s−1 or 7.9 × 1024 ions s−1. Dissociative recombination of N+2 produces neutral exothermic fragments that can escape from Triton. The rate is estimated to be 8.6 × 106 N cm−2 s−1 or 2.0 × 1024 atoms s−1. Implications for the magnetosphere of Neptune and Triton's evolution are discussed.