TY - JOUR
T1 - Discovery of proton hill in the phase space during interactions between ions and electromagnetic ion cyclotron waves
AU - Shoji, Masafumi
AU - Miyoshi, Yoshizumi
AU - Kistler, Lynn M.
AU - Asamura, Kazushi
AU - Matsuoka, Ayako
AU - Kasaba, Yasumasa
AU - Matsuda, Shoya
AU - Kasahara, Yoshiya
AU - Shinohara, Iku
N1 - Funding Information:
Part of this work was done at the ERG-Science Center operated by ISAS/JAXA and ISEE/Nagoya University. This study was supported by Grants-in-Aid for Scientific Research (15H05747, 15H05815, 17H06140, 17K14402, 20H01959, and 20K14546) of the Ministry of Education, Culture, Sports, Science, and Technology in Japan. This study was supported by JSPS Bilateral Open Partnership Joint Research Projects.
Publisher Copyright:
© 2021, The Author(s).
PY - 2021/12
Y1 - 2021/12
N2 - A study using Arase data gives the first observational evidence that the frequency drift of electromagnetic ion cyclotron (EMIC) waves is caused by cyclotron trapping. EMIC emissions play an important role in planetary magnetospheres, causing scattering loss of radiation belt relativistic electrons and energetic protons. EMIC waves frequently show nonlinear signatures that include frequency drift and amplitude enhancements. While nonlinear growth theory has suggested that the frequency change is caused by nonlinear resonant currents owing to cyclotron trapping of the particles, observational evidence for this has been elusive. We survey the wave data observed by Arase from March, 2017 to September 2019, and find the best falling tone emission event, one detected on 11th November, 2017, for the wave particle interaction analysis. Here, we show for the first time direct evidence of the formation of a proton hill in phase space indicating cyclotron trapping. The associated resonance currents and the wave growth of a falling tone EMIC wave are observed coincident with the hill, as theoretically predicted.
AB - A study using Arase data gives the first observational evidence that the frequency drift of electromagnetic ion cyclotron (EMIC) waves is caused by cyclotron trapping. EMIC emissions play an important role in planetary magnetospheres, causing scattering loss of radiation belt relativistic electrons and energetic protons. EMIC waves frequently show nonlinear signatures that include frequency drift and amplitude enhancements. While nonlinear growth theory has suggested that the frequency change is caused by nonlinear resonant currents owing to cyclotron trapping of the particles, observational evidence for this has been elusive. We survey the wave data observed by Arase from March, 2017 to September 2019, and find the best falling tone emission event, one detected on 11th November, 2017, for the wave particle interaction analysis. Here, we show for the first time direct evidence of the formation of a proton hill in phase space indicating cyclotron trapping. The associated resonance currents and the wave growth of a falling tone EMIC wave are observed coincident with the hill, as theoretically predicted.
UR - http://www.scopus.com/inward/record.url?scp=85109029606&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85109029606&partnerID=8YFLogxK
U2 - 10.1038/s41598-021-92541-0
DO - 10.1038/s41598-021-92541-0
M3 - Article
C2 - 34188084
AN - SCOPUS:85109029606
VL - 11
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 13480
ER -