Author:
Ding G.F.,Ye Y.,Chen R.,Xu G.S.,Yu Y.,Lin X.,Yang Q.Q.,Zhang W.,Li Y.,Yan N.,Liu S.C.,Wang L.,Zhang T.,Zhou T.F.,Wu D.G.
Abstract
Abstract
Helium Beam Emission Spectroscopy (He-BES) diagnostic has
been developed on EAST, which is able to measure the edge electron
density and temperature profiles simultaneously using a helium line
intensity ratio method. The diagnostic includes the beam injector
and the detection system. There are 20 observation channels within
an observation range of 80 mm in the detection system at the low
filed side, which can cover the whole scrape-off layer (SOL) and
part of the pedestal region of EAST. The beam injector system has
been upgraded to Supersonic Molecular Beam Injector (SMBI) system to
realize deeper helium injection since the 2021 campaign. Four
spectral lines at wavelengths of 728.1 nm, 706.5 nm, 667.8 nm and
656.3 nm are detected by the He-BES. The first three spectral
lines, including 728.1 nm, 706.5 nm, 667.8 nm, are measured for
calculating edge n
e and T
e profiles based on the
collisional-radiative model (CRM) model, and the last spectral line
(656.3 nm) is used for the measurement of D
α
emission. The edge electrostatic fluctuations can be obtained from
the power spectrum of D
α emission. The electron density
and temperature profiles calculated from the 667.8/728.1 and
728.1/706.5 nm line ratios are in good agreement with those from
other diagnostics in the edge region of plasma. The self-consistency
of He-BES diagnostic is also verified, such as the density pump out
caused by LHW and the lower edge temperature caused by the lower
heating power.