Concept Study for an Advanced Mass and Ionic Charge Composition Experiment (AMICCE) for Future NASA Missions, 15-R9583

Principal Investigators
Mihir I. Desai
Frédéric Allegrini
Arik Posner
David J. McComas

Inclusive Dates:  10/01/05 – Current

Background - Solar energetic particles (SEP) associated with coronal mass ejections or CMEs occur with little or no advance warning, and are often accompanied by high-energy ions that pose severe radiation hazards for humans and hardware in space. Recently, composition measurements from NASA's Advanced Composition Explorer (ACE) spacecraft have provided compelling evidence that the source material for such CME-related SEP events originates from the ubiquitous suprathermal tail between 2 to 100 keV/nucleon. Presently, however, properties of the suprathermal tail are not well known mainly because current solar wind instruments are relatively insensitive in the 2 to 100 keV/nucleon energy range, while energetic particle instruments use solid-state detectors with high (50 to 100 keV) lower-energy thresholds. These new findings have inspired numerous scientific investigations and prompted competing hardware groups to participate in a frantic race to be the first to measure and explore the uncharted suprathermal energy region. In addition, at present the ionic charge state and isotopic composition of the accelerated ion populations in the 0.1 to 10 MeV/nucleon energy range are typically obtained by two or more large instruments on the same spacecraft, e.g., SEPICA and ULEIS on ACE collectively weigh about 60 kg. However, such instruments are highly unlikely to fly on future NASA missions.

We propose here to investigate the feasibility of an innovative concept for a single lightweight (less than 15 kg) instrument that can measure the ionic charge state, isotopic, and elemental abundances of both, the suprathermal and the energetic particle populations in the heliosphere. A single instrument that makes detailed composition measurements of the as yet unexplored suprathermal tail between 8 to 100 keV/nucleon and of the energetic ions between 0.1 to 10 MeV/nucleon will provide a much needed breakthrough in making charged particle measurements in the heliosphere. Our new instrument – Advanced Mass and Ionic Charge Composition Experiment (AMICCE) – will easily meet the scientific requirements of 3 or more separate state-of-the-art instruments, and will therefore provide SwRI with enough flexibility to remain within the stringent payload allocation for a variety of upcoming NASA and European heliospheric missions.

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

• Optimization and simulations of the electrostatic analyzer (ESA)
• Optimization and simulations of the Time-of-Flight (TOF)
• Design, fabrication, and testing of the ESA prototype
• Publication of results in a scientific refereed journal

Accomplishments - AMICCE combines an innovative design for an electrostatic analyzer (ESA) with time-of-flight and residual kinetic energy measurements (TOF/E). We created a three-dimensional electro-optics model of the ESA and the TOF section. We performed nearly end-to-end simulations including most of the effects of the different components of the sensor and showed that the concept was working according to our expectations and was meeting our initial requirements. We determined that a collimator between the ESA and the TOF section was necessary. We are in the process of refining our design goals and optimizing the ESA to meet the resources allocated for similar instruments in the recent Science Definition Team report for the Inner Heliospheric Sentinels Mission, which is the next scheduled mission in NASA's International Living with Star Program.

2006 Program Home