L. Ives

Design of a gridded gun and PPM-focusing structure for a high-power sheet electron beam

We describe the design of a gridded electron gun and periodic permanent magnet (ppm)-focusing structure to create and guide a 415-kV, 250-A sheet beam with a cross section of 100 mm /spl times/ 8 mm. The gun is intended for use with a 40-MW X- band sheet beam klystron for driving accelerators. Using the three-dimensional (3-D) code suite AMAZE, we designed a ppm structure that guided the beam over 80 cm with 98% transmission.

Novel TWT interaction circuits for high frequency applications

Summary form only given. The initial focus of this program is on the development of Ka-band TWTs producing 10 W of RF power. These devices would potentially be used as RF sources for phased array antennas. This requires innovative TWT designs, which result in improved repeatability, increased yield and reliability, and reduced cost over existing Ka-band devices. To do this, the batch nature of micro-electro-mechanical systems (MEMS) fabrication techniques is ideal. However, many TWT interaction circuits, such as the conventional helix, are not compatible with MEMS techniques. Thus, Calabazas Creek Research, Inc. (CCR) has computationally investigated several innovative TWT interaction circuits based on MEMS fabrication. These include the square helix, planar helix and modified folded waveguide circuits.

A selectively metallized, microfabricated W-band meander line TWT circuit

The development of a selective metallization process capable of metallizing only the top of a microfabricated, raised meander line ridge is described. This fabrication process has unique potential in the development of millimetre-wave and terahertz regime slow wave structures for travelling wave tubes. The fabrication process will be described and the latest images and measured data will be presented.

650 GHz traveling wave tube amplifier

Calabazas Creek Research, Inc. (CCR) and the University of Wisconsin, Madison (UW) are developing a 650 GHz traveling wave tube amplifier (TWTA). Simulations predict 360 mW peak output power with a 2-10% duty cycle. This paper summarizes the design and fabrication of the TWT. Testing is expected in November, 2008.

Microfabricated W-band traveling wave tubes

Two research programs are in progress to develop W-band travelling wave tubes (TWTs). One uses a folded waveguide (fwg) slow-wave circuit, and the other uses a novel, planar meander line circuit. Both devices are currently being assembled. The predicted performance, fabrication methods and challenges, and measured data to date will be presented.

Development of Terahertz backward wave oscillators

Summary form only given. Calabazas Creek Research, Inc.is funded by NASA to develop efficient, light-weight, backward wave oscillators (BWOs) for applications from 300 GHz to 1.5 THz. These devices are needed as local oscillator sources in heterodyne receivers. Above 100 GHz, only BWOs have broad tunability (over 100 GHz) and high output power (/spl sim/1 mW); however, existing sources are heavy, consume excessive power, require water cooling, and have poor output mode purity. The technical objectives of the current program are as follows: incorporate a depressed collector to improve the efficiency and eliminate water cooling; improve the electron gun and configuration of the circuit to increase interaction efficiency; improve the output coupling to increase mode purity; and reduce the magnet system size and weight. A solid model of the final BWO configuration is detailed in this paper. The BWO operates in a 1.1 Tesla, flat magnetic field provided by a permanent magnet. The device operates at 3000-6000 V and is predicted to produce 6-8 mW of RF power continuously from 600-700 GHz.

Design of a permanent magnet gyrotron for active denial systems

Current W-Band active denial, non-lethal weapon systems use gyrotron sources requiring superconducting magnets. The long start-up time of the magnet is a major hindrance for rapid deployment of these systems. Calabazas Creek Research, Inc. is funded by the U.S. Department of Defense to develop a permanent magnet gyrotron as an alternate source.

Confined flow multiple beam guns for high power RF applications

Summary form only given. Multiple beam (MB) guns are finding increased application in different types of microwave tubes. The advantages of NIB guns in a microwave tube, for example, in a klystron (MBK), is a decrease of beam voltage, reduced power densities, and lower voltage gradients. Another advantage is increased bandwidth. Double convergent MB guns are capable of providing lower cathode loading and higher Rf power at a given frequency. At present all known MBKs use Brillouin type focusing, where the cathode is shielded from the magnetic focusing field. This type focusing is seldom used in single beam, high power klystrons due to inferior beam transmission as compared to the confined flow type focusing. This program is focused on developing confined flow multiple beam guns for RF power levels in excess of 50 MW at X-Band. A number of advanced, computational tools are used to model and refine the electric and magnetic field configural ions and transport electrons through the 3-D structure. A multiple beam gun configuration was achieved that provided confined flow beam transport through a simulated device without beam interception. Efforts are now focused on refining the modeling capability and improving the beam quality. Progress to date will be reported.

W-band MEMS-based TWT development

Summary form only given. Calabazas Creek Research, Inc. is funded by the U.S. Air Force to develop advanced, wideband, high frequency, micro-electro-mechanical systems (MEMS)-based traveling wave tubes (TWTs) for the transformational communications architecture. Specifically, the program is developing an 83.5 GHz TWT. Full power testing of the TWT in a solenoid magnetic field by Boeing Satellite System, Inc. is planned in 2004. Following successful completion, PPM focusing will be implemented and development of a device for space qualification will begin. The program is scheduled for completion in April 2005. Successful completion of this program will increase the operating range and applications for vacuum-based RF devices.

Advanced terahertz backward wave oscillators

Calabazas Creek Research, Inc. is funded by the National Aeronautics and Space Administration to develop efficient, light-weight, backward wave oscillators (BWOs) for applications from 300 GHz to more than I THz. These devices are needed as local oscillator (LO) sources in heterodyne receivers. BWOs have broad tunability (over 100 GHz) and high output power (/spl sim/1 mW); however, existing BWOs are heavy (over 20 kg), consume a lot of power (270 W), require water cooling, and have poor output mode purity. The technical objectives of the current program are as follows: utilize advanced manufacturing techniques to extend the operating range to frequencies exceeding 1 THz; incorporate a depressed collector to improve the efficiency and eliminate water cooling; improve the output coupling to increase coupling efficiency and mode purity; and reduce the magnet system size and weight. During the Phase I program, techniques were developed to couple the power from the slow wave circuit and transform the RF wave into a purely Gaussian output mode.