2012 IR&D Annual Report

MASPeX Detector Development, 15-R8288

Principal Investigators
Hunter Waite
John Roberts
Keith Pickens
Gregory Miller

Inclusive Dates:  02/06/12 – Current

Background — The purpose of this project is to develop a new microchannel plate (MCP) based, high-dynamic range detector to be incorporated on SwRI's multi-bounce high-resolution time-of-flight mass spectrometer (MBTOF). The detector development is in support of the NASA-funded MASPEX and the MBTOF instrument as well as other potential flight programs that require a ruggedized high dynamic range TOF detector. The MASPEX technology development program is developing key technologies necessary to increase the readiness of the instrument suite to TRL 6 by demonstrating the entire system performance in the target environment. The detector will be designed to meet both the performance and environmental requirements for a MASPEX-based space flight mission profile. This includes the ability to subject the detector to the equivalent launch loads, and bake the detector to ensure a contamination free environment within the mass spectrometer. The MASPEX detector incorporates two stages of amplification to meet the science requirements for measurement of ion ratios that require high dynamic range. The first stage of amplification and its collector are used to measure species at high abundance, while the second stage of amplification and its dedicated collector are used to measure the low abundance species. The second stage of amplification is protected from damage due to excessive ion currents by a blanking grid that is activated when the signal exceeds a current value. Significant overlap between the two stages ensures that the signal falls within the linear response range.

Approach — Once the detector is fabricated, SwRI will perform a baseline optical performance test for the detector using the existing MBTOF-III instrument as a test platform. The performance envelope of the detector will be established and recorded, and its dynamic range performance will be verified against the minimum performance requirement. The detector will then be subjected to vibration testing and temperature cycling. The detector will be instrumented and observed during testing to watch for visible or detectable anomalies that take place during testing. Upon completion of environmental testing, the detector will again be installed into the MBTOF-III instrument for performance measurement. The performance level will be compared to the baseline performance level to verify that the detector's performance has not degraded or otherwise changed significantly from the baseline.

Accomplishments — The mechanical design of the ruggedized detector has been made. The material properties of the ceramics used in the construction have been selected that meet or exceed the requirements for baking out the detector at high temperature to ensure cleanliness. All materials have been selected for low outgassing requirements. A finite element model has been made to model the loads expected on the detector. The microchannel plate requirement documents have been written for use in the fabrication of the microchannel plates used in the detector.

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