The war in Ukraine has reconfigured global flows of oil and gas. Less visible has been its impact on another supply chain: that of the so-called rare gases—neon, krypton and xenon—which are used in everything from chipmaking to medicine to space propulsion. Russia and Ukraine have long been big suppliers, accounting for about 40-50% of the global supply of neon before the conflict, and 25-30% of xenon and krypton, according to John Raquet of Spiritus Consulting, an industrial-gas specialist. At times, their share of the supply of neon has been as high as 70%. Hence the concern, after Russia’s invasion,...