Textbook in PDF format This book is intended to provide an introduction to some of the concepts and technologies involved in the development of high-power microwave sources and to describe some of the recent progress in the field. This will include microwave sources operating in both the high-peak power short-pulse, low-repetition rate and high-average power long-pulse, high-repetition rate or continuous-wave regimes, even though the instantaneous. There has been considerable interest recently in high power microwave (HPM) sources for nonlethal directed energy weaponry applications. Many of these sources that are being developed are derivatives of sources that are well known to the vacuum electronics community. The technology that is used to drive such sources has its roots in pulsed power, and a comprehensive understanding of their behavior requires the use of tools that have been developed in the plasma physics community. The ever-increasing reliance on the use of microprocessors that have increasing density of circuits packaged on a chip makes such systems increasingly vulnerable to HPM