This book deals with the latest developments in the design of power semiconductor thyristors, and has been written with both specialist device designers and power electronics circuit engineers in mind. The author begins by outlining the basic characteristics of thyristors, and the physics of their operation, and goes on to devote the main part of the book to their design and manufacture. He presents this information so that it is easily accessible both to experienced experts in the field, and to those who are approaching power thyristors for the first time. The emphasis of the book is practical, and the author stresses the considerations which should be borne in mind when designing thyristor devices. All types of such devices are covered, including for example the GTO, ASCR, GATT, and LASCR. Although the book is aimed at engineers working in the power electronics industry, it may also be of interest to academic researchers in the field. To enable readers to study particular topics in greater detail, a comprehensive reference list is included.