Development of an Advanced Space Weather Warning System: The PreSTIM Laboratory Prototype, 15-R9557

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Principal Investigators
Frédéric Allegrini
Mihir I. Desai
Arik Posner
Dave McComas

Stefano Livi
Nick Paschalidis
Applied Physics Laboratory, Johns Hopkins University

Inclusive Dates:  07/01/05 – Current

Background - Explosions – coronal mass ejections and flares – on the surface of the sun can release large amounts of energy and mass into the interplanetary medium. A fraction of these perturbations will inevitably impact directly on the Earth's magnetosphere. Geospace, the region surrounding our planet with a magnetosphere, is a protective environment that shields the upper atmosphere and low-Earth orbit against the solar wind and energetic particles. Under solar storm conditions, when transient solar activity impacts and transforms the magnetic bubble, the reaction of the Earth's environment is, at times, violent and dangerous. Changing magnetic fields induce currents, and this is also true for the ionosphere (the uppermost layer of the Earth's atmosphere). These currents can interfere with human technology on the Earth's surface and in space. Mainly, the positions of the radiation belts, carefully avoided by human space mission planners, become uncertain and often suddenly interfere with human presence in space. Severe radiation damage to humans and their support systems can result and needs to be avoided. Such severe space weather conditions can only now be forecast well in advance, with the Pre-Shock Suprathermal Ion Monitor (PreSTIM) placed on upcoming space weather monitoring missions. In this research project, we want to bring PreSTIM from the concept level to a fully functional laboratory prototype. The development of the PreSTIM is done in collaboration with the Applied Physics Laboratory (APL) at Johns Hopkins University.

The traditional way to derive kinetic energy (E), mass (m) and charge (q) is to determine the mass-per-charge by selecting a certain E/q, the TOF of the particle over a known distance, and the total kinetic energy with a solid-state detector. The PreSTIM concept of measuring suprathermal ions is entirely new. We use the stopping power of two carbon foils in combination with a newly designed ion optics aperture to separate ion species and determine individual fluxes. The sophisticated ion optics configuration separates ions in energy-per-charge so that they are ordered when they enter the TOF section with nearly parallel paths. Knowing the energy loss of the particle in the carbon foils, we can derive the kinetic energy, the mass, and the charge of the particle.

Approach - To achieve our goal, we divided the project in four objectives:

Objective 1. Modeling and optimization of the instrument. For this task we will perform electro-optics simulations with the powerful software Simion. The model of the instrument will include carbon foil effects (energy straggling and angular scattering of the particles). We will also simulate time-of-flight measurements to estimate the mass resolution of this instrument.

Objective 2. Design and fabrication of laboratory prototype. Based on the results of the first objective, we will design and build a laboratory prototype.

Objective 3. Integration of detectors and electronics and tests with ion beam. The detectors will be integrated into the laboratory prototype in a clean area and the tests with ion beam will be carried out in a high vacuum chamber.

Objective 4. Extension of the research on suprathermal ions.

Accomplishments - We created a three-dimensional electro-optics model for the laboratory prototype. We used the model to test different design options to determine the optimum configuration within our parameter space. We optimized the electro-optics of both the ESA and the TOF section. We have started the mechanical design of our laboratory prototype in parallel. The ESA is about to be tested in our vacuum chamber with ion beams. PreSTIM is a sensor that improves the capabilities for forecasting interplanetary shocks at Earth. A previous study with data from the STICS experiment on the Wind spacecraft showed that suprathermal foreshock ions provide early warning for incoming shocks. However, this study was limited to data obtained during the rising phase of the solar cycle. We have extended this analysis using the WIND/STICS dataset and demonstrated that measurements from instruments like PreSTIM will serve as an excellent Space Weather Monitor and will accurately forecast the arrival of upcoming space storms during other phases of the solar cycle as well.

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