Particle Detectors
type: Concept

THEMIS-SST
type: Concept
definition: [Source: NASA THEMIS home page, http://www.nasa.gov/mission_pages/themis/spacecraft/SST.html ] The Solid State Telescope (SST) measures superthermal particle distribution functions, namely the number of ions and electrons coming towards the spacecraft from specified directions with specified energies within the energy range from 25 keV to 6 MeV. These particles are the much more energetic (hence superthermal) than the main magnetospheric population, but are quite important as tracers of acceleration and heating in the magnetosphere. SST observations help us achieve the objectives of the THEMIS mission by providing two different measurements of substorm onset within the Earth’s plasma sheet, a region of enhanced particle fluxes and depressed magnetic field strengths within the Earth’s magnetotail. The first method is based on the fact that the plasma sheet slowly thins prior to substorm onset, but rapidly expands at onset. Using the so-called ‘finite gyroradius’ effect, the SST can remotely sense the location and motion of the boundaries of the plasma sheet, in particular the expansion at substorm onset. This is the first time that two SSTs will track this changing boundary from three locations while other instruments at different locations in the magnetosphere are determining the time of substorm onset. Group: Instrument_Details Entry_ID: THEMIS-SST Group: Instrument_Identification Instrument_Category: Solar/Space Observing Instruments Instrument_Class: Particle Detectors Short_Name: THEMIS-SST Long_Name: THEMIS Solid State Telescope End_Group Group: Associated_Platforms Short_Name: THEMIS End_Group Online_Resource: http://www.nasa.gov/mission_pages/themis/spacecraft/SST.html Online_Resource: http://themis.ssl.berkeley.edu/instrument_sst.shtml Sample_Image: http://www.nasa.gov/images/content/168041main_SST-FM1_med.jpg Creation_Date: 2008-08-13 Group: Instrument_Logistics Instrument_Owner: NASA End_Group End_Group
in scheme: instruments