Figure 3
On-axis fundamental undulator wavelength in nanometers (color bar) versus undulator period and electron beam energy in the synchrotron light source. A hybrid undulator model with a full gap of 4 mm is assumed. For a gap of 7 mm the radiation wavelength is approximately doubled. The undulator parameter K is approximately linear with the undulator period and in the range 4–15. For CHG schemes, the modulator period has to match a seed laser wavelength presently available at wavelengths not shorter than ∼240 nm. At beam energies below 3 GeV, this implies λu > 8 cm and 2–3 m in length. Similarly, beam energies lower than 3 GeV favor a more compact radiator. For example, emission at the third harmonic of the seed laser at 3 GeV requires λu > 6.5 cm and several meters in length. |