Next Besides high brightness, synchrotron-light possesses many other attractive properties. For example, each anpplication of X-rays can be optimized by selecting the best possible wavelength for its implementation. Therefore, it would be convenient to change the source wavelength as desired. Electrons oscillating in a radio antenna emit one single wavelength. Similarly, an electron circulating in the ring might be expected to emit a well-defined wavelength.
Radio amateurs know that a short pulse corresponds to a wide band of frequencies.
In the case of light, a wide band of frequencies also means a wide band of wavelengths.