TECHNOLOGY AREAS: Information Systems, Materials/Processes, Electronics

ACQUISITION PROGRAM: Directed Energy Weapons and Radar Systems

OBJECTIVE: Develop an end-to-end, self-consistent, physics-based analysis and design capability and methodology to model high-power multiple beam Inductive Output Tube�s (IOTs) and to quantitatively characterize and optimize their performance.

DESCRIPTION: The multiple-beam IOT (MB-IOT) has been identified as a key technology to provide high RF power for emerging applications, such as compact linear accelerators and directed energy weapons on future naval platforms. However, there are no computationally efficient, self-consistent, physics-based design tools available to design and reliably predict the performance of this device. This is due to many factors, including the disparate spatial scales and complex 3D geometry of the RF gridded gun and the complex evolution of emission, acceleration and collective energy extraction that span widely ranging time-scales. For example, the scale of the anode-cathode gap relative to the fine features of the grid can exceed two orders of magnitude, which is a challenge to both RF and particle beam simulation and necessitates use of conformal-mesh codes. Four key issues must be addressed for a full simulation: (1) frequency domain simulation of the RF input circuit, (2) self-consistent time-domain particle emission and tracking in RF and DC fields from the cathode through the beam tunnel, (3) self-consistent non-linear evolution of the multiple-beam phase-space and energy extraction through the output cavity, and (4) collector modeling.

PHASE I: Develop an end-to-end, self-consistent, physics-based methodology to model multiple-beam IOT�s, in either fundamental mode or higher-order-mode operation. Operating frequencies of interest are 300 MHz to 1 GHz, at power levels of hundreds of kilowatts to several megawatts (CW). Identify existing codes that can form the basis for the design methodology and the features that must be added, modifications required, etc. Perform a 3D analysis and design of the RF input/gun circuit and develop a procedure for incorporating the results of this design into other software modules, which will be needed to address issues such as dynamic loading of the RF cavity by the multiple beams and collector design.

PHASE II: Complete the additions and modifications to the various design codes and modules, as identified in Phase I. Validate the resulting design tools by modeling an existing single-beam IOT and comparing the results with experimental data. Perform an end-to-end analysis and design of a MB-IOT, with performance parameters selected in collaboration with government technical personnel.

PHASE III: Follow-on activities should include the application of this M&S tool to the engineering design, fabrication, and testing of a high-power MB-IOT.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Commercial applications of multiple-beam amplifier technology include broadband high-power amplifiers for commercial satellite up-links and high-energy accelerators, where the low operating voltage is attractive due to reduced costs and increased reliability.

REFERENCES:
1. E. Wright, A. Balkcum, H. Bohlen, "Recent advances in MBK technology and their application to a 1-MW CW HOM-IOT for shipboard FEL systems"
Seventh Annual Directed Energy Symposium, Rockville, MD, October 18-21, 2004.

2. J.J. Petillo, E.M. Nelson, J.F. DeFord, N.J. Dionne, B. Levush, "Recent developments to the MICHELLE 2-D/3-D electron gun and collector modeling code," IEEE Trans. Electron Devices, vol. 52, no. 5, pp. 742�748, May 2005.

3. S.J. Cooke, K.T. Nguyen, A.N. Vlasov, T.M. Antonsen, B. Levush, T.A. Hargreaves, M.F. Kirshner, "Validation of the large-signal klystron simulation code TESLA", IEEE Trans. Plasma Sci., vol. 32, no. 3, pp. 1136-1146, Jun 2004.

KEYWORDS: modeling; simulation; IOT; MB-IOT; directed energy weapons; radar

TPOC: John Pasour
Phone: (202)404-4975
Fax:
Email: [email protected]
2nd TPOC: Eugene Nolting
Phone: (202)781-3175
Fax: (202)781-4566
Email: [email protected]

** TOPIC AUTHOR (TPOC) **

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