Analysis of Dα（Hα） spectrum emitted in front of the limiter in HT-7^＊

In order to understand the recycling and emission processes of hydrogen atoms in HT 7, spectral profiles of the Dα（Hα） line emitted in front of the limiter have been observed with a high-resolution spectrometer and simulated by using the neutral particle transport code DEGAS 2. The results show that four processes are necessary to interpret the Dα（Hα） line shape： 1） atom desorption, 2） molecular dissociation, 3） particle reflection, and 4） charge-exchange. The products of the first two processes are cold atoms which emit photons near the peak of Dα（Hα） line shape, and those from the last two are warm atoms contributing to the blue side of the spectrum. For a typical ohmic discharge （shot 68520 ne（0） ≈ 3× 10^19 m^-3. these components contribute 32%, 15%, 32% and 21%, respectively. Dα（Hα） line shapes under different plasma parameters are also discussed in this paper.

Analysis of DαHα spectrum emitted in front of the limiter in HT--7

In order to understand the recycling and emission processes of hydrogen atoms in HT--7, spectral profiles of the D$_{\alpha}$(H$_{\alpha})$ line emitted in front of the limiter have been observed with a high-resolution spectrometer and simulated by using the neutral particle transport code DEGAS 2. The results show that four processes are necessary to interpret the D$_{\alpha}$(H$_{\alpha})$ line shape: 1) atom desorption, 2) molecular dissociation, 3) particle reflection, and 4) charge-exchange. The products of the first two processes are cold atoms which emit photons near the peak of D$_{\alpha }$(H$_{\alpha })$ line shape, and those from the last two are warm atoms contributing to the blue side of the spectrum. For a typical ohmic discharge (shot 68520 $n_e (0)\approx3\times 10^{19}$\,m$^{ - 3})$, these components contribute 32{\%}, 15{\%}, 32{\%} and 21{\%}, respectively. D$_{\alpha }$(H$_{\alpha})$ line shapes under different plasma parameters are also discussed in this paper.