about

The Waves and Beams Division, headed by Dr. Richard Temkin, conducts research on novel sources of electromagnetic radiation and on the generation and acceleration of particle beams.

Gyrotron Research

The gyrotron is a novel source of microwave, millimeter wave and submillimeter wave radiation. Gyrotrons are under development for electron cyclotron heating (ECH) of present day and future plasmas as well as for high frequency radar. These applications require tubes operating at frequencies in the range 90-300 GHz at power levels of up to several megawatts. Dr. Michael Shapiro leads the gyrotron research group. Major issues in gyrotron research include: methods of increasing the power output of gyrotrons, methods of producing output beams from gyrotrons which are nearly perfect Gaussian beams; and methods for increasing the efficiency of gyrotrons. In gyrotron research, it is also critical to have a high efficiency mode converter that can transform the output mode of the gyrotron into a Gaussian beam in free space. A new idea for a gyrotron microwave window, a dome shaped window, is also under investigation. Low power gyrotrons, 10 to 100 W, at frequencies from 140 to 500 GHz are being built for use in electron spin resonance and nuclear magnetic resonance studies in collaboration with the MIT Magnet Lab. Research is also being conducted on gyrotron amplifiers using novel structures such as photonic bandgap structures and confocal waveguide.

High Gradient Accelerator Research

The High Gradient Accelerator Group is conducting research on a novel, 17 GHz, microwave driven, photocathode electron injector. This device, sometimes called an RF gun, can generate a 2 ps beam of 1-2 MeV, 50-500 A electrons at high repetition rate. A 26 MW, 17.1 GHz klystron power source drives the electron gun. The electron beam is either directly applied to microwave generation experiments or is used as an injector into a 17 GHz, 25 MeV high gradient accelerator built by Haimson Research Corporation. A photonic bandgap cavity has been built and tested for operation at 17 GHz. This novel structure may have considerable advantages over conventional microwave structures. This research supports the program to build new electron accelerators that can reach the TeV range of energies.

Theoretical Research

The Intense Beam Theoretical Research Group, led by Dr. Chiping Chen, has contributed very significantly to our understanding of coherent radiation generation and particle acceleration. Topics covered include coherent radiation sources (CARM, FEL, gyrotron, relativistic klystron, relativistic TWT), intense beam transport and beam halo formation, beam-beam interactions, cyclotron resonance accelerators, two-beam accelerators, photocathode design, and related topics. Research explores self-field-induced nonlinear resonant and chaotic phenomena in intense charged particle beams. This research supports the U. S. program to construct advanced accelerators and advanced coherent radiation sources such as free electron lasers.