Measurements of ion temperature and drift energy of hydrogen plasma by neutral beam probe spectroscopy

The ion temperature and the energy of gross drift motion of a fully ionized hydrogen plasma with a field-reversed configuration are measured from the observed Doppler profile of the Hβ line from charge exchange neutrals which are generated by a pulsed intense hydrogen beam with energy ∼400 eV. At the beam energy, the generated neutrals are almost hydrogen atoms in the ground state and they emit spectral lines via electron impact excitation. A Monte Carlo analysis shows that the obtained Doppler temperature of the charge exchange neutrals agree with the ion temperature within 6% accuracy. The measured ion temperature and drift energy of the plasma are typically 100 and 10 eV, respectively.