Hydrogen isotope recycling at a tungsten target.

Abstract: Hydrogen recycling has been studied focusing on the neutral behavior in front of tungsten target in the plasma–wall interaction simulator APSEDAS and the tandem mirror GAMMA 10. The line intensity of hydrogen Balmer series decreased toward the target corresponding to a decrease in the electron density in APSEDAS. The relative population of n =3 and n =4 increased and that of n =5 and n =6 decreased just in front of the target (Z <5mm). This might be attributed to the reflected atom or reemitted molecule from the target. In GAMMA 10, the intensity of hydrogen Balmer (Hα) line decreased exponentially with distance from the target with two decay lengths: ∼16mm and ∼53mm. These two short decay lengths are attributed to the fact that a fraction of the reflected atoms and atoms dissociated from molecules are at excited energy states. [Copyright &y& Elsevier]