We report an experimental investigation of the gain anomaly of lithiumlike and lasers in a recombining silicon plasma. We examined the spatial distribution of gain coefficients of the two lasing lines and found that the peak gain of the laser occurs closer to the target surface than that of the laser, which is contrary to the results predicted by simulation. This discrepancy, which to our knowledge was not pointed out before, was found to be relevant to the gain anomaly of lithiumlike-ion and lasers. A small prepulse was introduced to modify the state of a silicon plasma column with which the spontaneous-emission amplification of lithiumlike silicon ion and transitions was observed. The prepulse-induced behaviors were quite different for the two lines. These results suggest that the sensitivity of the gain of the laser to the plasma density and the population of the level tends to reduce the difference in laser gain between the and transitions predicted by standard atomic physics codes.
© 2000 Optical Society of America