Fig. 1. Schematic diagram of CRDS diagnostic system

Fig. 2. Snapshot of dual drive large area negative ion source on test bench

Fig. 3. Illustration of CRDS diagnostic bench run light

Fig. 4. Ring-down time signal with/without medium (color online)

Fig. 5. Evolution of hydrogen ion density with time

Fig. 6. Variation of hydrogen anion density with RF power

Fig. 7. Variation of hydrogen ion density with pressure in source chamber

Fig. 8. Variation of hydrogen ion density with bias voltage

Fig. 9. Variations of electron density (N_e) and electron temperature (T_e) in front of the PG with bias voltage and the sheath formed by the difference of plasma potential