English to French Science Science (general)

What is Kirlian photography? In essence, it involves high-voltage, highfrequency electricity that is applied to the underside of a plate made of an insulating material such as glass. When any conductive object (which could
be metal or any material containing water, such as part of the body) is placed on this plate, there ensues an electric discharge through the air where the gap is
narrow, close to the object. Light from this discharge can be recorded on a photographic film placed between the object and the electrified plate.

This much could have been expected. What was remarkable, however, was the discovery, made by Semyon and Valentina Kirlian in the 1940s, that the characteristics of the discharge varied with a person's physiological and mental states. The history, some
suggestions regarding the physics of this process and an application to studies on mental patients were described some 15 years ago by Dr Victor Adamenko.

je ne comprends pas bien la structure de la phrase ici, notamment 'the history'
merci !