A Comprehensive Study On The Detection Results Of High Energy Proton Trapping And Loss In Solar Synchronic Orbit

There is a relatively stable distribution structure for radiation belt protons, which is important for space activities. During solar energy particles events, radiation belt will be full filled with solar injected protons. Associated with the occurrence of geomagnetic storms, solar protons penetrate into magnetosphere even lower and sometimes will be trapped to form a new radiation protons belt. Observations showed that trapped protons can be up to several tens Me V, which will cause serious harm to the satellites and spacecraft. Geomagnetic storms can also lead to high energy protons loss. Research of protons trap and loss has important significance for people to further understand the response to disturbance of the radiation belt and to develop radiation belt model applicable to space weather service.It is the first time using FY-1 satellites and NOAA satellites joint observation data to carry out trapping and loss phenomenon research. Five significant events including Apr 2000、Jul 2000、Mar2001 and Oct/Nov 2003 are found and used to analyze the specific evolution process and characteristics of trapping and loss of protons. We also discuss the possible mechanism. We obtained 13 trapping events and 12 loss events by statistics of nearly one solar cycle from 2000 to 2011. Relationship between these statistical events and space environmental parameters are also discussed. The main research results as follows:1) Trapped protons appeared in space range of 1.75<l<3.Intensity of trapped protons is different for different trapping events. The significance events appeared in Apr 2000、Mar 2001 and Oct 2003,during that time the peak intensity of trapped protons less than 10 Me V are far more than peak intensity of SAA. For protons more than 10 Me V,the peak intensity of trapped protons never exceed the peak intensity of SAA. Using the joint observation, we speculate trapped protons upper limit energy may be less than 16 Me V. Trapping of proton exist obvious pitch angle distribution, because we find nearly no one trapping event through MEPED0 detector. Trapping will last long time maybe several months depending of intensity of trapping and effects of subsequent disturbance. Generally,variations of trapping intensity appears2 two stage-rapid reduction and slow decay.2) Direct-trapped model is more effective for explain most trapping events. Event of Mar 2001 may be have correlation to SC-injection model. In fact, we think there exist more than one mechanism effect trapping. Other mechanism can explain the obvious enhanced trapping protons, such as waves.3) Loss of protons can appear in range even to L~1.75,which caused by strong disturbance in Nov 20 th,2003. The extent of the loss is different corresponding different events. Loss mainly have effect on less than 140 Me V protons. Nearly no obvious loss is found for more than 140 Me V. The loss will gradually resume, but subsequent disturbance may cause deeper loss.4) Increase of magnetic field lines curvature which induce destruction of the first adiabatic invariant may can explain loss at L>2 for protons with more than 36 Me V. Yet, loss of lower energy or deeper loss appear less than 2 may be caused by destruction of the third adiabatic invariant.5) Trapping and loss of protons have close relationship with Dst_min value of geomagnetic activity.Strong storm with Dst_min<-200 can cause significant effects on proton dynamics, the stronger of the storm,the more spatial extent of trapping and loss appear. Not every solar particle event associated with storm can induce trapping.6) Solar energy particles are necessary seeds for trapping. In addition to this, other factors can affect the intensity of trapping. Solar energy particles may also affect the occurrence of loss, continuous injection of high flux protons from solar particles can balance the loss.7) During the trapping and loss, the dynamic pressure of solar wind more than 10 np, the southward interplanetary magnetic field value Bz<-20,substorm activity frequently AE>800. We find that strong dynamic pressure of solar wind can have great influence solar energy particles injection even more than Dst_min,which provide a possible explanation on trapping event appeared on Jan 2005,during that time Dst_min is-97 n T.8) Trapping and loss events occurrence frequently during solar maximum years and transition years from maximum years to minimum years. Trapping and loss mainly affected by solar activities with CME events.