Table 1.

The nominal and averaged measured parameters associated with the electron beam (before and after IFEL acceleration), the CO₂ laser, and the ICS X-rays are presented here for convenience.

Parameter	Unit	Value
Electron beam		Initial	After IFEL
Energy, Ue	MeV	52.0	81.7
Energy spread, $\delta \gamma =\frac{{\sigma }_{\gamma }}{{\gamma }_0}$	—	<0.005	0.028
Charge, Qe	pC	250	100
Bunch length, σt	ps	3	2.5
Normalized emittance, εn	mm-mrad	2.3 ± 0.1	2.4 ± 0.15
Transverse size at ICS IP, σx × σy	µm	140 × 170 (±10)	140 × 170 (±10)
Repetition rate	Hz	1	0.008
CO 2 Laser Pulse
Central wavelength, λL	µm	10.3
Energy, UL	J	1.02 ± 0.12
Pulse length, σt	ps	2.5
Transverse size at ICS IP, w0	µm	150
Repetition rate	min	1–2
ICS X-rays
Central energy	keV	11.6
Photons per shot	#	1.21 (±0.63) × 106
Opening angle, θ ~ 1/γ	mrad	3.4 ± 0.1