Measurement of gold M-band emission’s angular distribution

It is important to reduce the capsule preheating from gold M-band emission in inertial confinement fusion experiments. A flat-response X-ray detector consisted of particular compound filters and an X-ray diode was adopted to measure the evolution of gold M-band X-ray from different directions from laser entrance hole. The spectral response of detector is not exactly flat on gold M band, which will introduce uncertainty into the calculation. Thus, a calibration result was given that flatness degree of the spectral response was better than 10%. Less M-band energy was observed with the detectors with larger observation angles with respect to the hohlraum axis. Higher energy conversion efficiency of laser to M-band x-ray was observed in R-T hohlraum experiments than that in large hohlraum.