There is a need to develop high-efficiency, high-power rf sources for current and future synchrotron radiation light sources, free electron lasers, and spallation neutron source user facilities. At present, conventional circular-beam klystrons and inductive output tube (IOTs) are the technologies of choice for accelerators for physics research and applications. While a commercially-available, conventional, circular-beam IOT provides lower operating voltage, smaller size, and higher efficiency than a klystron, its output power is less than 100 kW. Beam Power Technologys innovative elliptic-beam IOT (EBIOT) will overcome the power limitation. Additionally, the efficiency of the elliptic-beam IOT interaction operating at a low voltage will be comparable to that of the conventional circular-beam IOT operating at a high voltage, which is 60% to 70%. Beam Power Technology (BPT), Inc. proposes to continue the study of megawatt-class continuous-wave (cw) elliptic-beam inductive output tubes that has been started with DOE Phase II SBIR grants SC-0000850 and SC-0000851. The proposed SBIR effort will be aimed at a 1 MW cw EBIOT at 704 MHz. The Phase I technical objectives include: (1) theoretical modeling and concept design of a gridded elliptic diode; (2) theoretical modeling and concept design of the elliptic-beam system; and (3) concept design of the proposed EBIOT. Phase II will consist of completion of the engineering design, and fabrication of the vacuum envelope of the proposed EBIOT. Additional resources will be needed to build and test the focusing magnetics and to test the completed EBIOT. The Phase II efforts will be carried out in collaboration with Argonne National Laboratory under the support of a consortium of vendors and suppliers specializing in the manufacturing of microwave devices. Commercial Applications and Other
Benefits: The proposed studies of a 1 MW cw 704 MHz elliptic beam IOT will further establish the figure of merit for megawatt-class continuous-wave elliptic-beam inductive output tubes. The demonstrations of elliptic-beam IOTs at higher power and higher efficiency/lower voltage will produce a new class of high-power, high-efficiency RF sources for the physics accelerator community. As a highly efficient device, elliptic-beam IOTs have the potential to replace conventional circular-beam klystrons, circular-beam IOTs and possibly multi-beam high-order- mode (HOM) IOTs for accelerator applications requiring highly efficient high power RF sources at or below 1.3 GHz. Furthermore, elliptic-beam IOTs have the potential to replace conventional circular-beam IOTs which are widely used for television broadcasting.
