TSUBASA(MDS-1) observations of the radiation belt during magnetic storms

Recently, in situ observation is required to investigate the fluctuation of the radiation belt. TSUBASA(MDS-1) measures magnetic field and high energy charged particle (electron, proton, alpha-particle) in equatorial plane from 500 to 36000km, so that, particle flux, pitch angle distribution, phase space density and it_fs equatorial distribution can be measured. Information of these measurement results is very useful in order to clarify the cause of the radiation belt fluctuation, especially high-energy electron. TSUBASA was successfully launched by H-IIA launch vehicle from the Tanegashima Space Center on February 4, 2002. TSUBASA was injected into an elliptical orbit called a geostationary transfer orbit (GTO), with a spin rate of 5rpm, which makes the satellite attitude stable. We will report the observation result of TSUBASA during magnetic storms, and which is applicable in proposed theory about radiation belt fluctuation will be examined.