Varian Associates

About: Varian Associates is a based out in . It is known for research contribution in the topics: Beam (structure) & Amplifier. The organization has 2160 authors who have published 2591 publications receiving 46002 citations.

Resonant loss for helix traveling wave tubes

Abstract: This paper describes a scheme for suppressing backward wave oscillations (BWO) in high-power, PPM focused helix traveling wave tubes. The scheme consists of lossy, resonant meander lines deposited on each of the helix support rods and located between each helix turn By varying the length of the line, it can be made to resonate at the helix circuit's π-mode frequency. In this way the "resonator" provides loss in the vicinity of the π-mode, thereby inhibiting backward wave interaction. Test results have shown at least a four-fold increase in the BWO start current for a tube employing this resonant loss scheme.

Effects of Intense Microwave Radiation on Living Organisms

Abstract: A search for deleterious effects upon animals exposed to intense microwave radiation was made and definite damage to the eye and to the testicle was found. Ten centimeters proved to be the most dangerous wavelength. The effects observed could be accounted for by the elevated temperatures produced by absorption of microwaves in the organism. A theory is presented in which these temperatures are calculated; fair agreement with experiment was obtained. This work demonstrates the need for caution on the part of those who work with intense microwave sources, and for the establishment of standards for the protection of personnel exposed to such radiation. The observations which are discussed below are made up of material most of which either has been or will be published elsewhere. The results are so important to radio engineers, however, that the writer feels justified in rewriting them for publication in PROCEEDINGS OF THE I.R.E., particularly since many of these results would otherwise appear only in the medical literature and would not be brought to the attention of the average radio engineer. A preliminary report on this work was published early in 1949.

Microwave beam tube having an improved fluid cooled main body

Abstract: The relatively soft metal main body portion of an X band linear beam tube, such as a traveling wave tube, is rigidly supported in axial alignment with the linear electron beam by means of a relatively rigid tubular support structure, as of stainless steel, disposed coaxially surrounding the main body portion of the tube. The main body portion of the tube, which contains the microwave interaction circuit, is formed of an out-of-round transverse section such that out-of-round surface portions of the main body are radially spaced from the inner tubular wall of the support structure to define fluid coolant passageways therebetween for cooling the main body and microwave circuit in use. The main body coolant passageways are connected in series with the flow of coolant between the electron gun, at one end, and the beam collector, at the other end, whereby cooling of the tube is facilitated.

Flame ionization detector with flame monitor

Abstract: A flame ionization detector including means for monitoring the flame condition, so as to enable ignition of an extinguished flame. An igniter coil is mounted proximate the burner nozzle of the FID, and thermocouple means are provided including a hot junction in thermal contact with the nozzle, and a spaced cold junction. Means are provided for applying an electrical potential to the igniter coil to enable ignition of the flame upon a flame-out condition being detected as measured by the thermocouple output. In a preferable embodiment, the ends of the igniter coil are connected to a pair of electrical leads, with the connection zones defining the hot and cold junctions of the thermocouple. This permits the same lead pair to provide both the potential enabling the igniter function of the coil, and the interconnection for the thermocouple output signal. The same lead pair may also be utilized to provide the biasing potential to the burner nozzle.