In this work,population coefficients of hydrogen’s n=3 excited state from thehydrogen collisional-radiative（CR）model,from the data file of DEGAS 2,are used to calculatethe photon emissivity coefficients（PECs）of hydrogen Balmer-α（n=3 → n=2）（Hα）.Theresults are compared with the PECs from Atomic Data and Analysis Structure（ADAS）database,and a good agreement is found.A magnetic surface-averaged neutral density profile of typicaldouble-null（DN）plasma in EAST is obtained by using FRANTIC,the 1.5-D fluid transportcode.It is found that the sum of integral Dα and Hα emission intensity calculated via theneutral density agrees with the measured results obtained by using the absolutely calibratedmulti-channel poloidal photodiode array systems viewing the lower divertor at the last closed fluxsurface（LCFS）.It is revealed that the typical magnetic surface-averaged neutral density at LCFSis about 3.5×1016m-3.
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