Possibility of attainment of anomalously strong directionality of amplified spontaneous radiation

A study was made of the divergence of amplified spontaneous radiation from an extended source. An Ar–N₂ mixture was excited by a high-intensity proton beam and it emitted ultraviolet radiation as a result of transitions in the second positive system of the N₂ molecule. The pump power density reached 2.2×10⁷W·atm^–1·cm^–3 and the length of the excited region was 30 cm. An anomalously strong directionality of amplified spontaneous radiation was observed: this directionality was 20 times higher than that expected on geometric grounds.