Rn image picker lib temp 465b31a0-4b5e-48ee-bbb4-b4c99149b386

Kicker magnets are

dipole magnet A dipole magnet is the simplest type of magnet. It has two poles, one north and one south. Its magnetic field lines form simple closed loops which emerge from the north pole, re-enter at the south pole, then pass through the body of the magnet. ...

s used to rapidly switch a

particle beam A particle beam is a stream of charged particle, charged or neutral particles other than photons. In Particle accelerator, particle accelerators, these particles can move with a velocity close to the speed of light. There is a difference between ...

between two paths. Conceptually similar to a

railroad switch A railroad switch (American English, AE), turnout, or (set of) points (Commonwealth English, CE) is a mechanical installation enabling railway trains to be guided from one Rail tracks, track to another, such as at a Junction (rail), ...

in function, a kicker magnet must switch on very rapidly, then maintain a stable magnetic field for some minimum time. Switch-off time is also important, but less critical. An injection kicker magnet merges two beams incoming from different directions. Most commonly, there is a beam circulating in a

synchrotron A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The strength of the magnetic field which bends the particle beam i ...

, in the form of a particle train which only partially fills the arc. As soon as the circulating particle train has passed the kicker, it is switched on so that an additional batch of particles may be appended to the train. The magnet must then be switched off in time to not affect the head of the train when it next rounds the synchrotron. An ejection kicker magnet does the opposite, diverting a circulating beam so it leaves the synchrotron. Almost always, an ejection kicker is used to eject the entire particle train, emptying the synchrotron. This means that it has the entire tail-to-head gap in the synchrotron to function, and the switch-off time is essentially irrelevant. However, it must hold a stable field for longer (one full rotation of the synchrotron), and must generate a stronger magnetic field, as it is used to eject a higher energy beam that has been accelerated in the synchrotron. The magnets are powered by a high voltage (usually in the range of tens of thousands of

volt The volt (symbol: V) is the unit of electric potential, Voltage#Galvani potential vs. electrochemical potential, electric potential difference (voltage), and electromotive force in the International System of Units, International System of Uni ...

s) source called a power modulator which uses a pulse forming network to produce a short pulse of current (usually in the range of a few

nanosecond A nanosecond (ns) is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, of a second, or seconds. The term combines the SI prefix ''nano-'' indicating a 1 billionth submultiple of an SI unit (e ...

s to a

microsecond A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is to one second, ...

and thousands of

ampere The ampere ( , ; symbol: A), often shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One ampere is equal to 1 c ...

s in amplitude). The current produces a

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

in the magnet, which in turn imparts a

Lorentz force In electromagnetism, the Lorentz force is the force exerted on a charged particle by electric and magnetic fields. It determines how charged particles move in electromagnetic environments and underlies many physical phenomena, from the operation ...

on the particles as they traverse the magnet's length, causing the beam to deflect into the proper trajectory. Because a kicker magnet applies a particular lateral

impulse Impulse or Impulsive may refer to: Science * Impulse (physics), in mechanics, the change of momentum of an object; the integral of a force with respect to time * Impulse noise (disambiguation) * Specific impulse, the change in momentum per unit ...

to the beam, to achieve a fixed deflection angle the strength of the kick must be accurately matched to the momentum of the particles. This is part of the power modulator's job.

References

* * Accelerator physics {{Accelerator-stub