Profiles of Stark-Broadened Balmer Lines in a Hydrogen Plasma

A stationary hydrogen plasma was generated in a high current stabilized arc and its temperature was determined spectroscopically from the diagnostics of the line and continuum radiation. Extensive measurements of the profiles of the Balmer lines ${\mathrm{H}}_{\beta }$ and $H_{\gamma }$ were made and show that recent improvements in the theory of Stark broadening describe the observed line shapes well. Electron densities determined from linewidth measurements are slightly higher than those derived from line-intensity measurements. In the covered range of electron densities from ${10}^{16}$-${10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$ and temperatures around ${10}^4$ °K the difference amounts to about 25% for ${\mathrm{H}}_{\gamma }$ and 12% for ${\mathrm{H}}_{\beta }$, for which a refined Stark-broadening theory is available. In addition, the intensity distribution in the distant line wings of ${\mathrm{H}}_{\alpha }$ and ${\mathrm{H}}_{\beta }$ was measured and compared with asymptotic formulas. Satisfactory agreement is obtained.