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
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
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
|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.
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.