The band structure of the A²Δ→X²Π system of the CH radical, the method of hydrocarbon flux measurement, and the modeling of hydrocarbon elementary processes are described. Reviews of recent research achievements are also presented. At JT-60U divertor plates, the chemical sputtering yields of not only CH₄ but also C₂H_y have been measured with simultaneous observation of the CH and C₂ bands. In the MAP-II device in the University of Tokyo, hydrocarbon-enhanced molecular assisted recombination processes have been qualitatively proved by comparison of the measured and the modeled CH band intensity.