Life Test System

Cathode Life Test Project
As a part of our cathode research, we needed a way to reliably and cheaply performance and life test the cathodes we build. The result is shown in the figure nearby. It is customized to process our standard test vehicle, another innovation, that incorporates a glass envelope and inexpensive CRT stem around four cathodes. In this way, we test four experimental cathodes in the same vacuum environment, and subject them to the same processing variables. Usually, one of the cathodes is a control, meaning it has known properties, while the others are experimental. The life test system is computer operated with enough sockets and channels to automatically read four cathode parameters on 48 cathodes each day. The software records this data and also produces a variety of graphs, such as cathode activity, IV characteristics, Richardson curves, Schottky plots, power vs. temperature, series profiles, etc.

Demountable Phosphor Screen Test Facility
This project involved design and construction of a high resolution electron gun with electrostatic deflection. The gun was mounted in a vacuum chamber. A gate value between gun and screen allowed the gun to be maintained at vacuum while the phosphor screens were removed and replaced. The project also involved design and construction of drive electronics with computerized control of various rasters, dot patterns, etc.

Electron Tube for Processing Inks and Dyes
We developed an electron tube that produced a flat, fan-shaped electron beam at high energy. This beam was allowed to pass through an electron window into the atmosphere. The energy was high enough that the free electrons traveled about 12 inches in air before they were slowed down and absorbed. In this distance, they were sufficiently energetic and numerous to cure inks and polymers that could not be cured with UV on account of their opacity.

Electrostatically Focused Traveling Wave Tubes

Electrostatically focused coupled cavity traveling wave tube
This device provides broadband amplification at microwave frequencies (above 1 GHz) at intermediate power levels (50 watts to 1,000 watts). It answers a curious deficiency in the broadband amplifier market. Below 50 watts, the market is well supplied with solid state power amplifiers. Above 1,000 watts, conventional traveling wave tubes become economical, while below 1,000 watts, conventional TWTs become expensive on a dollar per watt basis. Above 50 watts, solid state devices also become expensive, as well as unreliable. By utilizing cathode ray tube construction technology and eliminating magnets, TWT cost drops significantly. We investigated a double helix TWT, a double ring loop TWT and a coupled cavity TWT. We built several prototypes. The photo above shows our coupled cavity version.

High Power Microwave Window Project
This was a Navy contract to develop a ceramic window capable of withstanding 5000 watts CW at about 10 GHz. We have designed, fabricated, tested and shipped about 100 of these windows to date. In the course of building up a test facility, we designed and built a resonant ring that allows the amplification of microwave power by about 15 to one.

Laser Cathode Ray Tubes
These tubes utilize an electron beam-stimulated, solid state laser at their output, in place of the phosphor screen normally used. They produce a field of intense collimated light. We designed and built the electron tubes that utilize these laser screens.

Line Cathode Project
This project involved developing a process to cataphoretically coat tungsten wires with triple carbonate material, then mounting these wires under tension in a flat panel CRT. We designed and built the spring plates and the electrical backplane for collimating the electron flow and shipped about a dozen devices to the customer.

Miniature CRT Screen Deposition
e beam inc. perfected a process for cataphoretic deposition of fine grain phosphors. Pursuant to this, we began making screens for a miniature CRT made by Tektronix, Inc., and we eventually shipped about 300 units.

Moving Mask Color CRT
We designed and built the world's first moving mask color CRT. This is a novel way to generate full color images at high brightness and resolution with only one electron gun. The slotted mask moves sideways via piezo-actuators inside the vacuum envelope. The slots align with phosphor stripes of a given color and allow the electron beam to write that color field. Then, the mask moves over and stripes of a different color are uncovered and written, etc.

Multibeam Electron Tubes
We have over the years built a variety of experimental electron tubes that employ a multiplicity of electron beams. We built a cathode ray tube that utilized 8 electron beams and used a segmented aperture grid for control and modulation. The largest device had 80 electron beams with independent modulation, focusing and deflection on each beam.

Multibeam Electrostatically Focused Klystron

Multibeam electrostatically focused klystron prototype
Multibeam klystrons provide larger bandwidth, more efficiency and lower voltage than conventional single beam klystrons. However, they are hard to focus magnetically, and the magnets add significantly to weight, size and cost. Can multibeam klystrons be focused without magnets, by electrostatic lenses alone? Our studies indicated that they could. We proposed such a device to NASA: a three-cavity oscillator operating at 5.8 GHz. It is designed for 2,000 watts of output, but we believe power levels can go much higher. We were awarded a contract to build two prototypes. The device is especially suitable for space missions where weight and size are critical factors. Combining the multibeam approach with electrostatic focusing is a way to increase total beam power while at the same time maintaining effective control of the beams. Electrostatic focusing works best when individual electron beams are small and of modest current and power. Our klystron prototype is shown in the photo, above.

Oxide Cathode Improvement Project

Oxide cathodes
This was done under NASA contract and consisted of two parts. The first part was to develop a cathode assembly with heater power consumption under 0.5 watts that could be used in low-power, expendable traveling wave tubes for phased array antennas. The second part of the project was to explore new cathode coating materials. A compound containing Indium and Scandium oxide was discovered that gives significant improvement in life. Our oxide cathodes are shown in the photo at left.

Phase measurement system

Phase Measurement System
Testing phase linearity and tracking in pulsed microwave devices is a difficult measurement. We developed a computer driven system that acquires phase vs frequency information, analyzes the data and plots it in a number of formats. About fifteen of these phase measurement systems have been built and sold to date. The phase measurement system is shown in the photo at right.

Reservoir Cathode Project
Reservoir cathodes utilize a porous tungsten plug to dispense barium to the cathode surface, just as impregnated dispenser cathodes do. The difference is that reservoir cathodes store the unused barium in a chamber behind the tungsten matrix instead of in the pores of the matrix itself. This allows far more barium to be stored and gives the cathode, in principle, unlimited life. The cathode is the main life-limiting component in all electron tubes. We developed, under NASA contract, a miniature reservoir cathode capable of unprecedented life and emission current density.

X-ray Tubes
We have over the years developed components and complete tubes for commercial customers. In particular, we developed a micro-miniature cathode that was to be used in an X-ray tube for placement in the human body.

Copyright 2005, ebeam, Inc.