Mid-infrared laser heterodyne spectrometer by hollow optical fiber and its newly designed coupler.

We demonstrate a newly designed, to the best of our knowledge, hollow optical fiber coupler for a mid-infrared (IR) laser heterodyne spectrometer that mixes a targeted light source with local oscillator (LO) light. The hollow fiber achieves a high transmission efficiency ∼80-90/, not only for a coherent laser source but also for an incoherent blackbody source. The branching characteristics of the hollow optical fiber coupler are found to be strongly dependent on the curvature and length of the input port fiber, indicating that the branching ratio could be designed independently for each input port.

Cross-Energy Couplings from Magnetosonic Waves to Electromagnetic Ion Cyclotron Waves through Cold Ion Heating inside the Plasmasphere.

Using a novel wave-particle interaction analysis, we show observational evidence of energy transfer from fast magnetosonic waves (MSWs) to low-energy protons in the magnetosphere. The analysis clearly indicates that the transferred proton energies are further converted to excite electromagnetic ion cyclotron waves. Since MSWs are excited by hot ions, cross-energy coupling of ions occurs through MSWs.

Discovery of proton hill in the phase space during interactions between ions and electromagnetic ion cyclotron waves.

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.

Visualization of rapid electron precipitation via chorus element wave-particle interactions.

Chorus waves, among the most intense electromagnetic emissions in the Earth's magnetosphere, magnetized planets, and laboratory plasmas, play an important role in the acceleration and loss of energetic electrons in the plasma universe through resonant interactions with electrons. However, the spatial evolution of the electron resonant interactions with electromagnetic waves remains poorly understood owing to imaging difficulties. Here we provide a compelling visualization of chorus element wave-particle interactions in the Earth's magnetosphere.

Repeated injections of energy in the first 600 ms of the giant flare of SGR 1806-20.

The massive flare of 27 December 2004 from the soft gamma-ray repeater SGR 1806-20, a possible magnetar, saturated almost all gamma-ray detectors, meaning that the profile of the pulse was poorly characterized. An accurate profile is essential to determine physically what was happening at the source. Here we report the unsaturated gamma-ray profile for the first 600 ms of the flare, with a time resolution of 5.