CAVITY MAGNETRON

-Nagendra Singh Shekhawat 09ec000597

Microwave Tubes

Ordinary gridded

tube(triode at the highest frequency)

Interaction between an

electron beam and RF field

takes place(klystron)

The interaction between an

electron beam and RF field is

continuous(TWT,MAGNET

RON)

An electric field is used to ensure that interaction between an electron beam and RF field is continuous(TWT,BWO)

A magnetic field ensures a constant electron beam and RF field interaction(MAGNETRON)

Invention of Magnetron

•Limitations of Ordinary Gridded Tubes-Skin Effect-Transit Angle Effect•Need of High-power microwaves

Velocity-modulated Tubes

Brief History of magnetron

•1920s:American Engineer Albert W. Hull invented the first magnetron while working for General Electric.

•1940s:Two physicists, John Randall and Harry Boot, working at the University of Birmingham, England developed a much more powerful magnetron that is compact enough to fit into ships, planes and submarines.

Cavity Magnetron

PHYSICAL STRUCTURE-

Anode-made of copper platesCathode-made of high emission materialMagnetsCavitiesFilament LeadsOutput antenna(waveguide)Cooling finsDC voltage source

Working of Cavity Magnetron

1.Production and Acceleration of an electron beam in a dc field

2.Velocity-modulation of the electron beam

Electron bunch formation

3.Formation of electron bunches by velocity modulation (Space-charge wheel)

4. Dispense energy to the ac field

Equations of electron motion

•Hull cut-off voltage equation V0c=B0

2b2(1-(a/b)2)2e/8m

•Hull cutoff magnetic equation B0c=(8V0m/e)1/2/ b(1-(a/b)2)

Strapping & Modes of Oscillations

Applications

•Radar

Applications

•Microwave oven-Everytime you warmSomething in microwave oven,you use a device that helped to Change the course

Of history of WW2

Applications

•Sulfur Lamp

The Large Hydron Collider

•Gigantic Scientific instrument near Geneva

•To study the smallest known particles-the fundamental building blocks of all things.

Working Of Accelerator

•Main Components1. Radiofrequency(RF) cavities and electric

fields2. Vacuum Chamber3. Magnets