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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This all happens in the ‘reflection room’ – the electrons are decelerated to zero electrostatic force in opposite direction to motion and then accelerates the electrons by electrostatic repulsion back to the cavity.

A cloud of thermionic electrons is generated by heating a filament inside a vacuum tube. These oscillations cause an electrostatic field across the grid gap of the cavity that changes direction at the frequency of the cavity.

Regardless of how we produce the LC circuit the physics works the same way. Electrons entering a half-cycle later, when the polarity is opposite, encounter an electric field which opposes their motion, and are decelerated.

In practice, of course, this is never the case because in practical systems there is always a loss.

Refled using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. After passing through the resonant cavity they are reflected by a negatively charged reflector electrode kljstron another pass through the cavity, where they are then collected. The residual kinetic energy in the electron beam when it hits the collector electrode represents wasted energy, which is dissipated as heat, which must be removed by a cooling system.

In higher modes of operation the electron bunches are formed more slowly.

The magnetron in your microwave cooker used to produce the microwaves and the resonant cavity they cook in and of course the LNB of your satellite system that clever little bit that collects the signal reflected from the dish.


The electron beam is modulated as it was in the other types of klystrons by passing it through an oscillating resonant cavity, but reclex the similarity ends.

Microwave Engineering – Reflex Klystron

You may have noticed that there are grids connected to the cavity. The electrons moving at higher velocities travel further beyond the grid before reversing direction because they have greater momentum.

Reflx 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. A klystron uses one or more special cavities, which modulate the electric field around the axis the tube.

Without this information klstron klystron would not be properly tunable, and hence not perform well, if at all. The physical dimensions of the cavity determine the frequency. Those moving at slower rerlex, such as the electron at time 4, move only a short distance from the grid before being affected by the repeller voltage. Klystrons make use of the transit-time effect by varying the velocity of an electron beam. How Reflex Klystron works Ask Question.

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 C and inductor L. I don’t understand how the velocity of the electron is modulated when it passes through the cavity for the first time.

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. How quickly it can do this depends upon the values of L and C. In the reflex klystron the electron beam passes through a single resonant cavity. The changing electrostatic field affects the electrons in the beam rerlex they pass through the grid gap. The operation of Reflex Klystron is understood by some assumptions.

When this happens, the electron is forced by the repeller voltage to stop, reverse direction, and return toward the grid. Klystron tube technologies for very high-power applications, such as synchrotrons and radar systems, have since been developed. Initially this alternating field in the cavity is produced when the first electrons ‘kick’ the cavity into resonance like plucking a string, or hitting a drum. The choice of mode is determined by the difference in power available from each mode and the band of frequencies over which the circuit can be tuned.


For the klystrode, see Inductive output tube.

Radar Basics – Klystron Amplifier

The reflex klystron operates in a different mode for each additional cycle that the electrons remain in the repeller field. The electrons are fired into one end of the tube by an electron gun. The beam then passes through a “drift” tube, in which the faster electrons catch up to the slower ones, creating the “bunches”, then through a “catcher” cavity.

Electrically, this is similar to the two cavity oscillator klystron with a lot of feedback between the two cavities. For very high frequencies where the skin effect dominates highly conductive materials such as gold and silver are used for construction. This energy in the LC system changes as it moves between the two devices.

Suppose you could watch the whole procedure in slow motion and see the electric and magnetic fields. The reflex klystron klystrpn known ilystron a Sutton tube after one of its inventors, Robert Sutton was a low power klystron tube with a single cavity, which functioned as an oscillator.

The electric field due to the accelerating mesh acts on all electrons to produce an approximately constant speed. This microwave generator, is a Klystron that works on reflections and oscillations in a single cavity, which has a variable frequency.