Impurity behavior is one of key issues for fusion devices. Many experiments on impurity transport have been performed in tokamaks and stellarators. Impurity injection (laser blow-off, impurity pellet injection and so on) is one of the typical transient transport study techniques. These conventional methods, however, have several disadvantages, such as a broad source profile of the injected impurities and difficulty in estimating of the total impurity amount injected. The properties of local impurity transport with a fairly high-accuracy could be obtained by means of the tracer-encapsulated pellet (TESPEL) injection, which has been utilized previously on the CHS and now on the Large Helical Device (LHD). TESPEL consists of polystyrene (-CH (C₆H₅) CH₂-) as outer shell and tracer particles as an inner core. The essential point of the diagnostics is based on a tracer particle source, which is poloidally and toroidally localized within a limited small volume of the plasma on the order of 1cm³. The behavior of impurity tracer ions deposited locally in the core plasma by means of TESPEL injection can be measured by the observation of the line emission due to charge exchange reaction of injected impurity nuclei, I (nuclear charge Z) with the hydrogen atoms, H (assumed to be in their ground state) introduced by the neutral beam injection (NBI):
I^Z++H_1s→ I^(Z-1)++H⁺
This method allows us to estimate the local impurity transport coefficients, which is already obtained by Li III (λ_Li=449.9 nm) on CHS. In TESPEL CXRS experiments with the Li tracer on LHD, however, Li III emission in the visible spectral range could not be measured due to the low S/N ratio and the other reasons. According to the theoretical optimization of the TESPEL CXR signals for various impurities in the visible spectral range under the conditions of the LHD plasma, the TESPEL CXRS experiments with tracer materials, such as Fluorine (λ_F(n=10→9)=479.3 nm) and Magnesium (λ_{Mg(n=12→11)}=478.9 nm), have been carried out. For comparison with our results, the CXR emissions of other materials after the impurity injection, such as the gas puffing and the pure pellet injection (Ne (λ_{Ne(n=11→10)}= 524.7 nm) and C (λ_C(n=8→7)=529 nm)), were investigated. From the previous experimental results, we can conclude that further optimization of the TESPEL CXR diagnostics in the visible range will give us more confidence in obtaining reasonable signals.