The Study Of Spectral Diagnostics Of Fast Ion In HL-2A

In tokamaks, fast ions are generated by injection of neutral beams, by rf acceleration, and by fusion reactions. They can be a major source of energy, momentum, and particles for the plasma Populations of fast ions are a source of free energy which we can not afford to waste, otherwise the Lawson criterion will not be satisfied and thus no fusion will occur. In ITER we expect the fast ion density will only constitute around 0.8% of the plasma density in the center, but at the same time the fast ions will carry approximately 15% of the kinetic energy available in the center of the plasma. These fast particles are expected to continuously slow down and deliver their energy to the bulk plasma, primarily to the electrons, through collisions,so the disgnosis for fast ion is a very important job.The principal challenge in a FIDA measurement is distinguishing the FIDA signal from other bright sources of light in the same spectral region. The intensity of the beam emission spectrum(BES) radiated by the injected neutrals and signal light from halo neutrals is typically much larger than the FIDA, Other contaminants in the spectrum include impurity lines, visible bremsstrahlung, and the very bright emission from atomic deuterium at the edge of the device. Impurity lines are usually removed by fitting. Visible bremsstrahlung is removed by background subtraction. The signal in our detected spectral range including fast-ion D? signal, the charge exchange spectrum signal of D?, D? signal from halo neutrals, beam emission spectroscopy of E、 E/2、 E/3 and the signal of CII, so first we use all these signals to fit our spectral signal get from spectrometer, after we fit the signal well, we use the total spectral signal plus all the signals except fast-ion D? signal, then we can get the signals we need.