From “whiskers” to “dust” - the critical role of dedicated diagnostic techniques in promoting paradigm shift

The development of theoretical models to explain complex physical processes is an essential part of the scientific method. However, such models must always be the subject of on-going scrutiny and experimental evaluation, and it is in this context that purpose-designed diagnostic techniques play a critical role. This paper presents an historical account of how this process has been crucial in the evolution of our understanding of the underlying physical mechanisms that control the behaviour of the high voltage vacuum gap.