Tags: Thesis And Antithesis EssayEssay Help ServiceCurfew Laws Argumentative EssayA 5 Paragraph Persuasive EssayI Need Help On My Math Homework For FreeCounter Argument In EssayResearch Papers On Animal TestingAerospace Engineer Research Paper
When the time of transit became an appreciable part of a microwave frequency cycle, performance degraded, forcing the designer to smaller and smaller sizes to achieve higher frequency.
The second major invention occurred in Russia with the realization that the citron relativistic mass change at high voltages could be fundamental to a new type of beam—wave interaction.
This led to the development of the gyrotron, later brought to a high state of development in this country.
For instance, repeatability of a measurement is challenging in microwave processing since the results can be affected by a myriad of factors, including moisture content, changes in dielectric properties during processing, electromagnetic interference with temperature measurements, sample size and geometry, or placement of the sample within the cavity.
The purpose of this chapter is to discuss, in general terms, how microwaves are generated, introduce the fundamental nature of microwaves, how they interact with materials, and how these interactions generate process heat.
The application of these fundamental concepts for design or selection of a practical processing system is discussed in Chapter 3.
The unique performance characteristics that arise from the interactions of microwaves and materials and how they may be used to develop application criteria are described in Chapter 4.
The spectrum of electromagnetic waves spans the range from a few cycles per second in the radio band to 10 Major advances in microwave generation and generators occurred in the early 1940s with the invention, rapid development, and deployment of the cavity magnetron on the heels of the earlier (1938) invention of the klystron.
What started as "flea powered" curiosities are now capable of generating hundreds of megawatts of power.
Large quantifies often lead to lower cost, and thus for many microwave heating and processing applications the magnetron is the device of choice, with advantages in size, weight, efficiency, and cost.
The magnetron is the major player in a class of tubes termed "crossed field," so named because the basic interaction depends upon electron motion in electric and magnetic fields that are perpendicular to one another and thus "crossed." In its most familiar embodiment, shown schematically in Figure 2-4, a cylindrical electron emitter, or cathode, is surrounded by a cylindrical structure, or anode, at high potential and capable of supporting microwave fields.