Electron temperature and density diagnostics in a helium glow discharge

Two laser-based diagnostics are used to determine the density (${\mathrm{n}}_{\mathrm{e}}$) and temperature (${\mathrm{T}}_{\mathrm{e}}$) of low-energy electrons confined in the negative glow of a dc helium glow discharge. Each diagnostic yields an independent relation between ${\mathrm{n}}_{\mathrm{e}}$ and ${\mathrm{T}}_{\mathrm{e}}$. From the intersection of these relations we find ${\mathrm{n}}_{\mathrm{e}}$=5×${10}^{11}$ ${\mathrm{cm}}^{\mathrm{-}3}$ and ${\mathrm{k}}_{\mathrm{B}}$ ${\mathrm{T}}_{\mathrm{e}}$=0.12 eV for an abnormal cathode fall of 261 V in 3.50-Torr helium.