cosmic ray storm
Technical term in astrophysics and space weather for a sudden increase in cosmic ray intensity, often associated with solar events.
Cosmic ray storms can occur due to solar flares.
宇宙線 (cosmic rays) is the general term for high-energy particles from space; 宇宙線嵐 specifically refers to a storm-like increase in their flux.
Compound of 宇宙線 (cosmic rays) and 嵐 (storm), directly translating the English term 'cosmic ray storm'.