Solar Wind and Pickup Ions (SWAPI)

SWAPI


SWAPI Instrument

 

The SWAPI instrument collects and counts two types of particles: ones from the solar wind flowing from the Sun and particles called pick-up ions (PUIs) that have entered the heliosphere from outside our solar neighborhood and traveled inwards where IMAP orbits near Earth.

These PUIs are mostly hydrogen and helium atoms that have lost one electron due to energy from a collision or being energized by the Sun. SWAPI is designed to vary its detector to select specific energies of these particles every few seconds.

How It Works

The charged hydrogen and helium (and sometimes larger) particles enter the SWAPI instrument parallel to the spin axis of the spacecraft. As IMAP spins in space, solar wind particles are swept into SWAPI through a special opening called “sunglasses.” The opening is covered by a screen with very tiny precise holes that cut down the brightness of the very intense solar wind. The incoming pick-up ions enter the device through the part of the opening which does not have the “sunglasses.”  The charged particles are then guided further into the instrument between two spheres. The paths of the particles are curved by the electrical charge setting on the inside sphere. Particles with energies either larger or smaller than the chosen setting either crash into the metal walls of the instrument or, if they have exactly the right amount of energy, they flow down to hit a carbon foil. This impact releases electrons which are then collected by a pair of devices called channel electron multipliers. Because electrons are so tiny, even a group of 1000 would not have a big enough signal for a sensor to pick up, so the charges need to be multiplied, or increased, to be detected. Only electrons detected by both channel electron multipliers are counted as incoming ions. This data is then transmitted to IMAP scientists on Earth where it is analyzed to determine the concentrations of helium and hydrogen coming from the Sun and from outside the heliosphere.

Learn more about swapi

Explore the SWAPI Model

How We Use SWAPI Data

By graphing the data collected using SWAPI, scientists like Dr. Jamie Rankin can determine the amounts of hydrogen and helium ions from the solar wind and the hydrogen and helium pickup ions at various possible energies. From this information, they can then determine the basic information of the solar wind at any moment, such as its temperature, density, and speed. Since the pickup ions come in from different directions, those characteristics of the solar wind partially determine the number of pickup ions that can travel in through the solar system to reach IMAP. Most of the pickup ions detected by SWAPI are helium because they are bigger than hydrogen and have more energy to travel upwind into the inner solar system where they can be detected.

 

Meet the Team

The SWAPI team, led by Dr. Jamie Rankin at Princeton University, is comprised of 25 engineers, scientists, and other supporting roles.

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It has been a roller coaster ride: lots of excitement to build and calibrate The Solar Wind and Pickup Ion (SWAPI) instrument collects and counts solar wind particles and pick-up ions (PUIs)., followed by many curious observations, followed by the team putting together plans to solve the problems, and then repeat. There’s never a dull moment working with SWAPI. Even in the ‘boring’ moment, I often find myself sitting back and simply admiring the beauty of this stunning instrument. Can’t wait to see operating SWAPI in space!

Dr. Lengying Khoo, Science and Hardware Team Member / Calibration Lead, SWAPI

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It has been a great experience for me! I love it that my science skills and lab skills all found their proper use during the work in the lab building and supporting The Solar Wind and Pickup Ion (SWAPI) instrument collects and counts solar wind particles and pick-up ions (PUIs).! Even when there are challenges I am confident in our great team’s quick and deft response with open communication and proactive mindset. This is the nicest and most supportive working environment I have ever been in; thank you very much Space Physics Lab at Princeton.

Dr. Mergen Alimaganbetov, Scientist and Hardware Team Member / An instrument which is used to discover that something is present somewhere, or to measure how much of something there is. Lead, SWAPI

Princeton Space Physics Group

The Princeton Space Physics group.

Image Credit: NASA/Princeton/Lengying Khoo