Abstract
The thermal spike hypothesis for the radiation compaction of vitreous silica by energetic ions is developed in detail. The variation of the thermal constants with temperature and the variation of energy dissipation along the range are considered and are found to affect the problem little. When the hypothesis was first presented, the thermal constants had not been determined, nor was the behavior of vitreous silica toward light ions known. The duration of thermal spikes calculated from current data is too short to account for the compaction by their thermal behavior alone. Therefore, the atomic nature of the processes is considered, and it is concluded that the process of compaction is facilitated and largely controlled by bond cleavage. However, the thermal excitation is essential in developing the configuration characteristic of the compacted state.