Electron density and temperature determination using the concept of particle confinement time uniqueness

The use of atomic hydrogen line emission to determine the particle confinement time τp of a tokamak plasma is a well-known diagnostic technique. Using such a method, for any one of the emission lines, be it from Lyman, Balmer, or Paschen series, the same (i.e., unique) value of τp must be obtained. Furthermore, this measurement is directly related to the local values of the electron temperature and density. We have developed a method based on the Hα, Hβ, and Hγ hydrogen line emissions and on the concept of τp uniqueness for a tokamak plasma, to determine the local electron density and temperature. The technique has been applied to plasma discharges generated in the NOVA-UNICAMP tokamak. The results show good agreement with measurements from multichannel Thomson scattering and Langmuir probe. A procedure to simulate the Hα emissivity radial profile using the obtained results is also discussed.