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.