This workshop brought together for the first time accelerator experts as well as experimental and theoretical high energy physicists from all over the world to consider the physics potential of high energy linear electron-positron colliders. A wide variety of physics cases were presented ranging from precision tests of the top quark and electroweak gauge bosons to searches of the intermediate mass Higgs bosons and supersymmetric particles.

Collider experiments have become essential to studying elementary particles. In particular, lepton collisions such as e⁺e⁻ are ideal from both experimental and theoretical points of view, and are a unique means of probing the new energy region, sub-TeV to TeV. It is a common understanding that a next-generation e⁺e⁻ collider will have to be a linear machine that evades beam-energy losses due to synchrotron radiation. In this book, physics feasibilities at linear colliders are discussed in detail, taking into account the recent progress in high-energy physics.

This report presents an update of the experimental achievements published in the review “State- of-the-Art of High-Power Gyro-Devices and Free Electron Masers”, Journal of Infrared, Millime-ter, and Terahertz Waves, 41, No. 1, pp 1-140 (2020) related to the development of gyro-devices (Tables 2-34). Emphasis is on high-power gyrotron oscillators for long-pulse or continuous wave (CW) operation and pulsed gyrotrons for any applications.

These proceedings aim to provide a comprehensive overview of research, technology and applications in the field of accelerators. Contributions from the entire field of accelerators are presented, including low and high energy machines, and medical and industrial accelerators.

Progress in Physics has been created for publications on advanced studies in theoretical and experimental physics, including related themes from mathematics.