Fig. 1. Schematic of experimental setup

Fig. 2. Temporal evolution of spectral line intensity of Fe I: 374.57 nm with and without hemispherical cavity confinement. (a) D=5 mm; (b) D=7 mm; (c) D=9 mm; (d) D=10 mm; (e) D=11 mm; (f) D=13 mm; (g) D=15 mm; (h) D=17 mm; (i) D=19 mm

Fig. 3. Relationship between the diameter of the hemispherical cavity and the delay time corresponding to the best enhancement factor

Fig. 4. Relationship between the diameter of hemispherical cavity and the best amplification of enhancement

Fig. 5. Two-dimensional spatial distributions of spectral line intensity. (a) Unconfined, Fe I: 374.57 nm; (b) unconfined, Fe II: 275.59 nm; (c) hemispherical cavity confinement, Fe I: 374.57 nm; (d) hemispherical cavity confinement, Fe II: 275.59 nm