Figure 3
From: Stable femtosecond X-rays with tunable polarization from a laser-driven accelerator
Spectral measurements: (a) typical spectrum, measured via single photon counting in the mixed gas. The data are fitted using a synchrotron function. (b) Critical energy for consecutive shots. Each circle represents the critical energy for one shot in pure helium, while crosses denote the mixed gas. Dashed lines show the average energy for helium (red) and the mixed gas (blue). The shaded area around these lines represents the standard deviation.
