Development of a 3Pi Ion Spectrometer, 15-9468

Principal Investigators
Philip W. Valek
Frederic Allegrini
Jerry Goldstein
David McComas
Oleg Vaisberg

Inclusive Dates:  04/01/04 - Current

Background - The current techniques used to make in situ measurements of space plasmas share a limitation in their field of view. The largest field of view of a single sensor yet flown is that of a "top hat" analyzer. The top hat analyzer can view a ring that encompasses 10 degrees of elevation and 360 degrees about its azimuth, allowing an instantaneous viewing of less than 10 percent of the plasma spatial distribution. To cover the total plasma distribution with such a limited field of view requires either scanning or multiple sensors. Either of these approaches requires more resources than would a single instrument with a larger field of view.

Approach - To better complete the measurements outlined above, we are developing a prototype instrument with an instantaneous field of view of 75 percent of space, or 3Pi steradians. We have divided our project into three challenges.

Challenge 1: Design and model electro-optics for a single plasma sensor capable of simultaneously viewing 3Pi (75 percent) of all space. The modeling of the sensor is performed with an electro-optic ray-tracing program.

Challenge 2: Build a prototype sensor capable of simultaneously viewing 3Pi (75 percent) of all space based on the results of Challenge 1.

Challenge 3: Perform a trade study to analyze different detector configurations and the impact on the measurement, i.e., sensitivity and resolution. This study will allow the design of the optics to be modified to respond to different mission opportunities.

Accomplishments - We have nearly accomplished Challenge 1. Multiple electro-optic configurations have been defined, each capable of viewing 3Pi steradians. Selected configurations have been iteratively modeled and ray traced to test the actual angular response and to optimize the electrodes used. We are in the final phase of selection of the specific electro-optical design for the physical prototype.

We have done some limited preparatory work to ensure we will be ready to fabricate our prototype (Challenge 2) after our design is finalized.

We have begun work for Challenge 3. Our work on electro-optical design led naturally to extensive discussions of how to incorporate the optics into a full sensor capable of making mass and energy measurements. In addition, our design phase has produced multiple configurations that meet our requirement for 3Pi steradian viewing, and we have already been engaged in some detailed discussion of how these different configurations would allow us to respond to different mission opportunities. We have identified key missions in which SwRI will have a definite competitive advantage.

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