A reflex klystron consists of an electron gun, a cavity with a pair of grids and a repeller plate as shown in the above diagram. ➢ In this klystron, a single pair of. 5 Mar Reflex klystron amplifier used in microwave systems for generating higher frequency that we can used further for various purposes in. To understand the operation of a reflex klystron I think you need to start with a basic understanding of a tuned circuit made up from a capacitor.

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Microwave Engineering – Reflex Klystron

This reduced power from the bunches, in turn, reduces the amplitude of the cavity oscillations and causes a decrease in output power. I don’t understand how the velocity of the electron is modulated when it passes through the cavity for the first time. The technique of amplification used in the klystron is also being applied experimentally at optical frequencies in a type of laser called the free-electron laser FEL ; these devices are called optical klystrons.

This causes some of the electrons to speed up when the field is in one direction and to slow down when its in the other direction. Electronic oscillators LC types are designed in such a way that a small amount of energy is fed back into the tuned circuit at the correct time phase.

This type of klystron oscillator is called a reflex klystron because of the reflex action of the electron beam. It sounds like the rf oscillation exists there already. Home Questions Tags Users Unanswered.

Reflex Klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode klystdon. After passing through the catcher and giving up its energy, the lower energy electron beam is absorbed by a “collector” electrode, a second anode which is kept at a small positive voltage.

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The function of the catcher grids is to absorb energy from the electron beam.

Some modern klystrons include depressed collectors, which recover energy from the beam before collecting the electrons, increasing efficiency. If that was all that happened the eeflex of the output would be very small. The electrons moving at higher velocities travel further beyond the grid before reversing direction because they have greater momentum. The electrons in the beam are velocity-modulated before the beam passes through the cavity the second time and will give up the energy required to maintain oscillations.

Retrieved from ” https: Provided there is no loss of energy these oscillations could in theory exist forever. Each device is capable of storing energy in some form FIELD – the inductor stores magnetic field, the capacitor stores an electric field.

Klystrons can produce far higher microwave power outputs than solid state microwave devices such as Gunn diodes. The electrons form bunches in this area when the accelerated electrons overtake the decelerated electrons. His resonator was called a “rhumbatron” by the Varian brothers. This effect is used to good advantage for automatic frequency control in receivers, and in frequency modulation for transmitters. Regardless of how we produce the LC circuit the physics works the same way.

OK it’s not really a mystery. The lower concentration of electrons in the returning bunches provides less power for delivery to the oscillating cavity. Some reflsx employ permanent magnets.

Klystron – Wikipedia

Sign up or log in Sign up using Google. Klystrons make use of the transit-time effect by varying the velocity of an electron beam. Their prototype was rrflex and demonstrated successfully on August 30, Potentiometer digital Variable capacitor Varicap. Klystron amplification, power output, and efficiency can be greatly improved by the addition of intermediate cavities between the input and output cavities of the basic klystron.


The reflex klystron operates in a different mode for each additional cycle that the electrons remain in the repeller field. In their return journey, the electrons give more energy to the gap and these oscillations are reflxe.

The floating drift tube klystron has a single cylindrical chamber containing an electrically isolated central tube. This phenomena of different types of energy continuously being interchanged not created or destroyed is the basis of all oscillatory systems. When this happens, the electron is forced by the repeller voltage to stop, reverse direction, and return toward the grid. The electron beam is accelerated towards the anode ref,ex.

The Reflex Klystron

The simplest klystron tube is the two-cavity klystron. When the grid field provides maximum deceleration, the returning electrons release maximum energy to the grid field which is in phase with cavity current. The location is determined by the transit time of the bunches at the natural resonant frequency of the cavities the resonant frequency of the catcher cavity is the same as the buncher cavity. The distance the electrons travel in the space separating the grid and the repeller depends upon their velocity.