Question

Bending magnet radiation e- Wiggler radiation e- 1 Undulator radiation

Simply explain the graphs and why the radiation produced is different for each of the three radiation sources.

Answer 1

The three graphs give a variation of photon flux with frequency.

Radiation produced is different in three cases, due to the variance in dependence of intensity.

Bending magnets: They are used to deflect electrons from their straight path when passing through these magnets. They emit a spray of X-ray tangentially to the plane of the electron beam.

Intensity here is proportional to the number of electrons, and we obtain such a variation.

1 α Nelectrons

Undulator: These are magnetic structures made of complex array of small magnets. They force the electron to move in an undulating/wavy trajectory. The radiation emitted at each bend overlaps and interferes with that from other bends.

Intensity here is dependent on both the number of electrons and square number of poles in the magnets, which explains such a graph.

× N. 0 electrons poles

Wiggler: It is a series of magnets designed to laterally deflect a beam of electrons. It produces a radiation like that of the bending magnets, but spectrum is broad due to contribution of many dipoles in the wiggler.

Intensity here is proportional to number of electrons and number of poles.

I o. Nelectrons × Npoles