Edward L. Ginzton

A Linear Electron Accelerator

The theory, design, and some experimental results relative to linear electron accelerators are discussed. It is shown that, though the orbits are unstable, this instability is so small as to be negligible in general, provided the electrons are injected at relativistic velocities. Likewise, space‐charge spreading may be neglected. The optimum loading design is found for various types of power feeds and curves are given by means of which any design may be evaluated. A number of illustrative cases are discussed. Operation of a low power, 38‐section accelerator is described.

Design and Performance of a High-Power Pulsed Klystron

This paper describes the design, theory, construction, and operation of multi-megawatt pulsed klystrons.

Reflex-Klystron Oscillators

A comprehensive analysis of reflex klystrons is developed by considering the electrons as particles acted upon by forces which modify their motion. The analysis is similar to earlier explanations of electron bunching in a field-free drift space and predicts a similar current distribution when bunching takes place in a reflecting field. The effect of the bunched electron beam is treated qualitatively by considering the effect of the beam admittance upon a simple equivalent circuit. A quantitative mathematical analysis based upon oscillator theory is also derived and the results are presented in a series of universal curves which are used to explain the operating characteristics of these tubes. Power output, efficiency, starting current, electronic tuning, and modulation properties are discussed. Some general remarks on reflex-oscillator design considerations are also included.

Velocity Modulated Tubes

Publisher Summary This chapter presents the theory of velocity modulation tubes (known as klystrons) and discusses its performance. The simplest form of the klystron is the two-cavity amplifier. The cathode acts as a source of electrons; between the cathode and the first cavity there is a d-c accelerating field, which, with the aid of a suitable focusing system, produces a beam of electrons that passes through two (or more) resonant cavities. Across the input gap, a time-varying electric field is produced by introducing some radio-frequency energy into the resonant cavity. This time-varying potential is normally small compared to the cathode-anode voltage and the changes in the velocity of electrons are therefore small. At this gap, there is usually little evidence of density modulation. Electron beams used in klystrons are of relatively high current density as compared to other commonly used beam devices, such as the cathode ray tubes and electron microscopes.

A Microwave Impedance Bridge

A six-arm waveguide structure is described which is a true microwave equivalent of a Wheatstone bridge. A theoretical analysis of the equivalent circuit of the device has been made, using the symmetry properties of the structure. The resulting relation among the admittances of the various arms is exactly that of a Wheat-stone bridge with shunting susceptances across each pair of terminals. A device of this sort for use at 10 cm has been built and tested, and was found to behave as predicted. With this bridge it is possible to measure any impedance to about the same accuracy as with a standing-wave detector. A valuable feature of this instrument is that the standard impedances required are three variable reactances (movable shorting plungers) and a Z0termination. The data are obtained in the form of three lengths, the positions of the movable shorts. Since the device is the complete equivalent of a Wheatstone bridge, it can also be used as a four-terminal lattice section in filter design or in any other related application requiring the microwave equivalent of a lattice section. This allows all the greater flexibility which lattice sections have, as compared to tee or pi sections commonly used in microwave work.

Development of High-Power Pulsed Klystrons for Practical Applications

This paper describes the development of three practical, sealed-off, tunable klystrons intended for operation in the region of 1 to 2 megw at the S, L, and X radar frequency bands. These tubes are an outgrowth of the previous development at Stanford of a 30-megw S-band klystron in conjunction with the billion-volt linear electron accelerator program. Similar design principles apply to all of these tubes, but the three smaller klystrons described make use of cavity tuning methods appropriate to the three frequency bands.

Microwaves--Present and Future

Many of us are so immersed in the ever-narrowing branches of electrical engineering that it is difficult to take stock of the accomplishments in the field as a whole or to visualize the possibilities and limitations of future developments. For those of us engaged in teaching and research, and who expect to remain in the field, such an assessment is necessary if we are to guide our students properly and anticipate the probable roles of our own specialties. I will review briefly present-day microwave applications indicating some of the spectacular developments during the past twenty years and try to make an appraisal of potential limitations in microwave research per se, and point to a possible profitable avenue of research for the future.