Ro and La Forge being subjected to anyon emissions.
Anyons are subatomic particles that can be used to eliminate chroniton fields.
In 2368, Lieutenant Commander Data used an anyon emitter to eliminate anomalous chroniton fields which were appearing at seemingly random locations aboard the Enterprise, after they had assisted a Romulan science vessel which had suffered an accident while attempting to utilize an experimental interphase generator. It was eventually discovered that, as a result of Lieutenant Commander Geordi La Forge and Ensign Ro Laren being "phased" by the generator, they were leaving chroniton fields in their wake every time they passed through a solid object. Using high-intensity anyon emissions, Data was able to de-phase La Forge and Ro. (TNG: "The Next Phase")