Theoretical Study On The Dielectronic Recombination Of Tungsten Ions

Dielectronic recombination （DR） is a basic atomic process in electron-ion collisions.The knowledge of accurate dielectronic recombination （DR） rates of heavy ions is crucialfor the study of ionization balance of highly ionized elements in hot plasmas. DR ratecoefficient is necessary physics parameter for studying rare plasmas ions abundancedistribution，it plays a important role to the simulation of magnetically confined plasma.Accurate data about DR process, such as strengths, cross sections and rate coefficients, isvery important parameters when one simulate and diagnose all kinds of plasmas anddevelop X-ray laser.Tungsten will be used for a certain plasma-facing components in the divertor regionof the International Thermonuclear Experimental Reactor （ITER）. For divertor plasmamodeling and radiative cooling studies, accurate atomic data for highly ionized tungstenions are essential, especially data on recombination processes that are a major source ofradiation losses.We investigate the use of the confguration-average distorted-wave approximation（CADW） method to calculate DR rate coeffcients for equal-core tungsten ions by usingthe Flexible Atomic Code （FAC）. The results are presented for DR rate coefficientscontributions of inner-shell electron excitation. For W39+ions, it can be seen that the DRrate coefficients are principal from4l shell excitations for kTe <800eV, where the DR ratecoefficients for4p subshell excitation are the largest, and the4s subshell excitation can notbe ignored. As the temperature increases, the DR rate coefficients for3l shell excitationincrease. The contribution from3l shell excitation is18%for the total DR rate coefficientsat kTe=1250eV, therefore, DR rate coefficient for3l shell excitation must be taken intoaccount. Moreover, the relative contribution from△n=2core excitation increasessmoothly with increasing temperature and is at most about23%.For W⁴²⁺ions, the contribution from4l shell excitation dominates at low electrontemperature, DR rate coefficient from4s subshell excitation is the largest. As thetemperature increases, the DR rate coefficients for3l shell excitation increase. The DRrate coefficient for3d excitation exceeds that for the4s subshell excitation at kTe=1250eV. For W⁴¹⁺ions, the contribution from4l shell excitation is the largest at low electrontemperature, As the temperature increases, the DR rate coefficients for3l shell excitationincrease, and3d shell excitation play an additional important role in the total DR ratecoefficients at high temperature. For W⁴²⁺and W⁴¹⁺ions, the largest contribution from△n=2core excitation is about26%and16%at high temperature, respectively.