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... > Instruments > Earth Remote Sensing Instruments > Passive Remote Sensing > Magnetic Field/Electric Field Instruments > Composition Analyzer > MMS HPCA

Preferred term

MMS HPCA  

Definition

  • The Hot Plasma Composition Analyzer (HPCA) is more concerned with detecting exactly which kinds of ions are present. It gathers more detailed measurements but at a slower rate. When an ion, hits the carbon foil at the front of the sensor, it knocks off an electron. The HPCA uses this electron to start a timer to measure the time it takes the original particle to hit a stop detector. This time can be used to determine the particle's speed, and this speed is used to determine the mass of the original particle. The mass, in turn, is used to determine what particle it was. The material in Earth's magnetosphere is dominated by a different set of atoms than the material streaming in from the sun with the solar wind: protons, singly-charged helium and oxygen in the magnetospheric plasma; protons and doubly-charged helium in the solar wind. Consequently, using the HPCA to observe what ions are present during any given event helps scientists determine which kind of plasma was involved, and assess the effects of particles of different charge and mass. Unlike FPI, the HPCA needs only one sensor. The instrument relies on the spin of the spacecraft to view a sweep of the sky, gathering a set of observations every 10 seconds, the equivalent of half of the spacecraft's spin. The HPCA also has a unique capability never before flown. There are usually so many solar wind protons compared to, for example, magnetospheric oxygen that mass spectrometers flown in the past were overwhelmed -- and the oxygen signal was masked. HPCA uses radio frequency oscillations to sweep the majority of solar wind protons away from the detector, without affecting the magnetospheric oxygen, resulting in a 10- to 100-fold improvement in detection. The HPCA was developed and built by the Southwest Research Institute in San Antonio, Texas. (en)

Broader concept

Change note

  • 2015-04-07 12:45:16.0 [mpmorahan] Insert Concept add broader relation (MMS HPCA [ffddbe98-056e-46d8-9fc1-27f6807ce0a7,157813] - Composition Analyzer [d9fca203-ace2-4d3e-8e5c-2c556ba3cf4b,157809]);
  • 2015-04-07 13:17:54.0 [mpmorahan] insert AltLabel (id: null text: Hot Plasma Composition Analyzer language code: en); insert Definition (id: null text: The Hot Plasma Composition Analyzer (HPCA) is more concerned with detecting exactly which kinds of ions are present. It gathers more detailed measurements but at a slower rate. When an ion, hits the carbon foil at the front of the sensor, it knocks off an electron. The HPCA uses this electron to start a timer to measure the time it takes the original particle to hit a stop detector. This time can be used to determine the particle's speed, and this speed is used to determine the mass of the original particle. The mass, in turn, is used to determine what particle it was. The material in Earth's magnetosphere is dominated by a different set of atoms than the material streaming in from the sun with the solar wind: protons, singly-charged helium and oxygen in the magnetospheric plasma; protons and doubly-charged helium in the solar wind. Consequently, using the HPCA to observe what ions are present during any given event helps scientists determine which kind of plasma was involved, and assess the effects of particles of different charge and mass. Unlike FPI, the HPCA needs only one sensor. The instrument relies on the spin of the spacecraft to view a sweep of the sky, gathering a set of observations every 10 seconds, the equivalent of half of the spacecraft's spin. The HPCA also has a unique capability never before flown. There are usually so many solar wind protons compared to, for example, magnetospheric oxygen that mass spectrometers flown in the past were overwhelmed -- and the oxygen signal was masked. HPCA uses radio frequency oscillations to sweep the majority of solar wind protons away from the detector, without affecting the magnetospheric oxygen, resulting in a 10- to 100-fold improvement in detection. The HPCA was developed and built by the Southwest Research Institute in San Antonio, Texas. language code: en);

URI

https://gcmd.earthdata.nasa.gov/kms/concept/ffddbe98-056e-46d8-9fc1-27f6807ce0a7

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