Haruhisa Matsumoto

One‐ and two‐dimensional simulations of electron beam instability: Generation of electrostatic and electromagnetic 2f p waves

We have performed computer simulations of the self-consistent nonlinear evolution of electrostatic and electromagnetic 2f p waves excited by electron beams with electromagnetic particle code. In both one- and two-dimensional periodic systems an electrostatic 2f p wave is generated at twice the wave number of forward propagating Langmuir waves by wave-wave coupling. This wave grows with the forward propagating Langmuir wave in the nonlinear stage of the simulations. The electrostatic 2f p wave in the simulations is saturated at about -20 ∼ -30 dB of that of the Langmuir waves. It is larger than the value expected from observations in the terrestrial electron foreshock. The electromagnetic 2f p wave is only excited in two-dimensional systems. The magnitude of the electromagnetic 2f p wave is correlated with the backward propagating Langmuir wave, not with the electrostatic 2f p wave. This result suggests that the electromagnetic 2f p wave is excited by the wave-wave coupling of forward and backward propagating Langmuir waves. The typical power density estimated from a reasonable amplitude of Langmuir wave is of the same order or much weaker than the value typically observed around the electron foreshock.

Total dose orbital data by dosimeter onboard Tsubasa (MDS-1) satellite

The total dose data from a Tsubasa (MDS-1) satellite, flying in a highly eccentric orbit, is analyzed. The total dose is measured by the small dosimeter using RADFETs. The RADFETs have been calibrated with the Co60 gamma ray source, and 56 devices (denoted DOS-S) were mounted in several experimental modules in the satellite. The total dose data behind certain Aluminum shield domes have been analyzed initially. The total dose change is affected by electron flux in the thin shield. In thicker shield, electron and proton affect the total dose profile.

SEE flight data from Japanese satellites

This paper reviews the SEE (Single Event Effects) which have been observed on Japanese spacecraft in space since 1971, and summarizes the in-orbit SEL (Single Event Latch-up) and SEU (Single Event Upset) data for 10 years from 4 Japanese satellites. The data is separated into solar maximum and solar minimum periods and into Galactic Cosmic Ray (GCR) and South Atlantic Anomaly (SAA) groupings. Heavy ion and proton testing of the same flight parts are reported. Prediction rates using CREME96 codes with heavy ion LET cross sections and 2-parameter fits and CREME96 to proton cross section data are compared with the SEE flight data. We have followed the suggestions of Petersen for a good comparison paper. The extreme value theory is applied for the prediction of the maximum SEE rates from solar flare events and can be used to discriminate the effects of the solar events from a quiescent. Environment, and can also be used to examine outlier data points.

Magnetic fluctuations embedded in dipolarization inside geosynchronous orbit and their associated selective acceleration of O+ ions

We study magnetic fluctuations embedded in dipolarizations in the inner magnetosphere (a geocentric distance of ≤6.6 RE) and their associated ion flux changes, using the Engineering Test Satellite VIII and Active Magnetospheric Particle Tracer Explorers/CCE satellites. We select seven events of dipolarization that occur during the main phase of magnetic storms having a minimum value of the Dst index less than −40 nT. It is found that (1) all of the dipolarization events are accompanied by strong magnetic fluctuations with the major frequency close to the local O+ gyrofrequency; (2) the magnetic fluctuations appear with significant amplitude in the component nearly parallel to the local magnetic field; (3) the strong flux enhancement is seen in the energy range of 1–10 keV only for O+ ions. In terms of frequency and dominant components of the magnetic fluctuations, they are considered to be excited by the drift-driven electromagnetic ion cyclotron (EMIC) instability that is recently identified with the linear theory. We perform particle tracing for H+ and O+ ions in the electromagnetic fields modeled by the linear dispersion relation of the drift-driven EMIC instability. Results show that the O+ ions are accelerated to the energy range of 0.5–5 keV and undergo a significant modification of the spectral shape, while the H+ ions have no clear change of spectral shape, being consistent with the observations. We therefore suggest that the electromagnetic fluctuations associated with the dipolarizations can accelerate O+ ions locally and nonadiabatically in the inner magnetosphere. This selective acceleration of O+ ions may play a role in enhancing the O+ energy density in the storm time ring current.

A very large scale flow burst observed by the SuperDARN radars

We examined the dynamics of the ionospheric plasma in the dayside sector by using the HF radar data at Iceland West and at Finland from 1100 to 1230 UT on September 5, 1995. During that period, the solar wind density was high and the IMF was strongly southward. The dayside magnetopause was highly compressed nearly to the geosynchronous orbit. The two radars simultaneously detected a poleward flow burst in the noon sector which, assuming uniformity of flow in the region of the data gap (1.5 MLT) between the two radars, showed a magnetic local time extent of 5 hours. This local time extent is 2 to 3 hours wider than previous results. The maximum poleward plasma velocity of the flow burst is ∼750 m/s, and the latitudinal size of the flow burst region is ∼100 to 200 km. This flow burst region initially expanded in longitude up to 5 hours, and then shifted poleward with a phase speed of 400 to 670 m/s. The flow burst has a duration of ∼20 min. This large-scale poleward flow burst is likely to be due to large-scale reconnection occurring at the dayside magnetopause and subsequent convection as the magnetic field lines are transported across the polar cap.

Low-latitude ionospheric effects of energetic electrons during a recurrent magnetic storm

We study a magnetosphere-ionosphere coupling at low latitudes during a moderate (corotating interaction regions/high-speed solar wind streams-driven) geomagnetic storm on 22 July 2009. Recently, it has been shown that during major (coronal mass ejection-driven) storms, quasi-trapped >30 keV electrons largely enhance below the radiation belt in the forbidden zone and produce an additional ionization in the topside ionosphere. In this work, we examine a case of the recurrent storm when the magnetosphere-ionosphere coupling through the quasi-trapped electrons also may take place. Data from NOAA/Polar-orbiting Operational Environmental Satellite and Japanese Greenhouse gases Observing Satellite were used to identify the forbidden electron enhancement (FEE). We find a positive vertical gradient of the electron fluxes that indicates to the radiation belt as a source of FEE. Using global ionospheric maps, radiotomography reconstructions from beacon data and COSMIC/FORMOSAT-3 radio occultation measurements, we have observed an unusually large area in the nighttime ionosphere with increased total electron content (TEC) and prominent elevation of the F layer at low latitudes that coincides with FEEs spatially and temporarily. Ionizing particles are considered as an addition source of ionization along with generally accepted mechanisms for storm time TEC increase (a positive ionospheric storm). We discuss relative contributions of the FEE and disturbance dynamo electric field in the TEC increases during the storm recovery phase.

Space radiation environment and its effects on satellites: analysis of the first data from TEDA on board ADEOS-II

The Advanced Earth Observing Satellite II (ADEOS-II) was launched into sun-synchronous, sub-recurrent orbit on December 14, 2002, and its operation terminated unexpectedly on October 24, 2003. While in orbit, the Technical Data Acquisition equipment on board ADEOS-II monitored the space radiation environment and its effects, including total-dose and single-event upset, recording them on 16 M and 64 M-DRAM memories. In this paper, we analyze the first data results from these monitors.

Measurements of Cosmic-Ray Neutron Energy Spectra from Thermal to 15 MeV with Bonner Ball Neutron Detector in Aircraft

Cosmic-ray neutron energy spectra from thermal to 15MeV were measured with a multimoderator spectrometer known as the Bonner Ball Neutron Detector (BBND) at aviation altitude (9–11 km). Four flights were carried out around Nagoya Airport in Japan. The measured data were unfolded using the maximum entropy deconvolution code MAXED, and the derived spectra agreed with the calculated results using the PHITS-based analytical radiation model in the atmosphere (PARMA). The results of the in-flight measurement verified the accuracy of model calculation in regard to the neutrons within a certain energy range.

Analysis of propagation delays of compressional Pi 2 waves between geosynchronous altitude and low latitudes

The propagation of compressional Pi 2 waves in the inner magnetosphere is investigated by analyzing the onset delay times between the ground and the geosynchronous altitude. We use the compressional component (northward) of magnetic data from low-latitude stations and the geosynchronous satellite ETS-VIII (GMLat. = -10.8°, GMLon. = 217.5°). The onset delays are determined by a cross-correlation analysis, and we analyzed the events with high waveform correlations (correlation coefficient greater than 0.75). Some of these high-correlation events have the properties of propagating waves; Pi 2 waveforms at the ground stations and the satellite were synchronized with each other when the data were shifted by onset delays. The results of the statistical analysis show that 87% of the Pi 2 onsets at a ground station (Kuju, GMLat. = 26.13°, GMLon. = 202.96°) were delayed from the Pi 2 onsets at ETS-VIII, and the average of the delay times was 29 sec. This clearly shows Pi 2 onsets (initial perturbations of Pi 2) propagated from the geosynchronous altitude to the low-latitude ground. The delay times tended to be larger around the midnight sector than around the dawn and dusk sectors. These results are consistent with two-dimensional propagation of fast waves estimated by the model of Uozumi et al. (J Geophys Res 114:A11207, 2009). The delay times are nearly identical to the travel time of fast waves from geosynchronous altitude to the low-latitude ground, and the local time variation of the delay shows the azimuthal propagation along the geosynchronous orbit. We conclude that the initial compressional perturbations of Pi 2 waves propagate radially and longitudinally as a fast wave in the inner magnetosphere.

Analysis of solar gamma rays and solar neutrons detected on March 7th and September 25th of 2011 by ground level neutron telescopes, SEDA-FIB and FERMI-LAT

At the 33rd ICRC, we reported the possible detection of solar gamma rays by a ground level detector and later re-examined this event. On March 7, 2011, the solar neutron telescope (SNT) located at Mt. Sierra Negra, Mexico (4,600 m) observed enhancements of the counting rate from 19:49 to 20:02 UT and from 20:50 to 21:01 UT. The statistical significance was 9.7sigma and 8.5sigma, respectively. This paper discusses the possibility of using this mountain detector to detect solar gamma rays. In association with this event, the solar neutron detector SEDA-FIB onboard the International Space Station has also detected solar neutrons with a statistical significance of 7.5sigma. The FERMI-LAT detector also observed high-energy gamma rays from this flare with a statistical significance of 6.7sigma. We thus attempted to make a unified model to explain this data. In this paper, we report on another candidate for solar gamma rays detected on September 25th, 2011 by the SNT located in Tibet (4,300 m) from 04:37 to 04:47 UT with a statistical significance of 8.0sigma (by the Li-Ma method).