Definitions

Dose is a quantity of radiation delivered at a position and in the context of space energetic particles radiation effects, it usually refers to the energy absorbed locally per unit mass as a result of radiation exposure. The energy may be transferred through ionisation and excitation, in which case it is often referred to as absorbed dose. When the energy absoption results in damage to the lattice structure it is commonly referred as Non-Ionising Energy Loss (NIEL).

A Single Event Upset (SEU) occurs when a sufficiently large burst of charge is collected on a critical node in one of the digital microcircuits on a chip. The critical charge is the minimum charge required to produce an SEU in a sensitive volume.

Surface charging is produced by plasma particles of any energy up to about 50 keV. High level charging is driven by differential current density between on one hand electrons with energies between 1 keV and 20 keV and on the other hand ions or photoelectrons or secondary electrons. Time scales to determine effect may range from milliseconds to hours.

Internal charging is produced by high-energy electrons, generally those over 300 keV, which are found throughout the inner and outer trapped radiation belts. The motion of these high-energy electrons along with the excited electrons/holes constitutes a current inside the solid. High-energy electrons, incident upon a thick dielectric, can produce a build-up of embedded charge which induces large potential differences throughout the material.

The table below is a summary of several charged particle effects and the parameters used to quantify them:

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