After the invention of the thermionic electron valve by Sir John Ambrose Fleming in 1904 almost 90 years have passed. During this period, the development of electron tubes created the so called 'Electronic Age'. Electron tubes played the leading role in the electronic appliances until the middle of the 1950's when solid state devices as transistors and integrated circuits replaced them. Now, at the close of their brilliant life, this book presents a collection of valuable research data, and developments in production and applications, contributed to by scientists and engineers engaged in the development and of the electron tube. Readers: electrical engineers, physicists.