Development of the Collective Interaction Klystron (CIK)

The CIK is a microwave source which relies on the negative mass instability for electron bunching, as opposed to the linear-drift ballistic bunching of conventional klystrons. A proof-of-principle (POP) CIK is being tested to verify the predictions of analyses, which indicate that the CIK is feasible in the 2-10-GHz region at megawatt to gigawatt power levels. Such a device can be quite compact, and 3D numerical simulations show strong particle bunching for efficient operation. The POP device is designed for a 500-keV, 100-A electron beam for an initial operation at 5 GHz. For maximum flexibility and to allow testing over a wide range of parameters, the POP device is modular, incorporating a multisection, helical beam tube to allow variation of the interaction length. Results of the analyses and status of the experiment are presented