What type of tube did Roentgen work with when he discovered x-rays?

Roentgen discovered x-rays while working with a Crookes tube, which is a type of vacuum tube. This tube was one of the earliest forms of electron tubes and played a crucial role in the development of early x-ray technology. The Crookes tube contains a low-pressure gas and has electrodes, which allowed for the observation of cathode rays. It was during an experiment with this tube that Roentgen noticed a fluorescent glow emanating from a nearby screen, leading to his landmark discovery of x-rays. The characteristics of the Crookes tube, including its ability to generate cathode rays, were fundamental to understanding the mechanisms that would later lead to the identification and application of x-rays in medical imaging.

Other types of tubes, such as Thomson or Geissler tubes, had their own specific uses in early physics experiments but did not relate directly to the discovery of x-rays in the same manner as the Crookes tube. For instance, the Thomson tube was associated with experiments on cathode rays, while Geissler tubes were primarily used for gas discharge studies.