Evidence for particle acceleration in the magnetospheric cusp

Abstract

Abstract. New evidence reveals that the charged particles can be energized locally in the magnetospheric cusp. The power spectral density of the cusp magnetic fluctuations shows increases by up to four orders of magnitude in comparison to an adjacent region. Large fluctuations of the cusp electric fields have been observed with an amplitude of up to 350 mV/m. The measured left-hand polarization of the cusp electric field at ion gyro-frequencies indicates that the cyclotron resonant acceleration mechanism is working in this region. The cyclotron resonant acceleration can energize ions from keV to MeV in seconds.

Energetic electrons in the exterior cusp: identifying the source

“…Chen (2008) showed that the large fluctuations in magnetic and electric fields observed in the cusp are often sufficient to energize particles up to several hundred keV in seconds through cyclotron resonance. Test particle simulations by Otto et al (2007) have shown the potential formed due to reconnection under northward IMF can also accelerate particles efficiently.…”

“…associated the presence of energetic ions with ULF wave intensity in the cusp and proposed a resonance source energizing the population within the exterior cusp. Further studies of wave properties in the CDC (Vogiatzis et al, 2008;Chen, 2008) have shown the conditions are often sufficient to energize both ions and electrons up to the observed energies. Additional evidence for local acceleration was provided by Chen and Fritz (2001) and who showed the energetic population was composed of both ionospheric (O + ) as well as solar wind (He ++ , O >+3 ) ions.…”

Reply to S. Fuselier et al.'s comment on "Energetic particle sounding of the magnetospheric cusp with ISEE-1"

“…Chen and Fritz, 1998;Chen, 2008;Vogiatzis et al, 2008), but more work is needed to fully understand a source that could produce both ions and electrons with the observed energies. Independent of the full dynamics of a cusp energization source, the observations of particles in this region give strong evidence that particles are accelerated locally.…”

Dissipative kinetic Alfvén solitary waves resulting from viscosity

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] For example, Chen et al 19 examined the kinetic Alfv en wave instability driven by a field-aligned current in high b plasmas. Hollweg and Kaghashvili 20 examined the density fluctuations of a linearly polarized Alfv en waves in a shear flow.…”