Development of broadband ultrashort-pulse reflectometer for inductively coupled plasma

We have applied an ultrashort-pulse reflectometer (USRM) to an inductively coupled plasma for density profile measurement along with a plasma absorption probe (PAP). It is found that the density in the edge plasma region measured by USRM is in good agreement with that by PAP, however, the measured density in core region shows large discrepancy between two methods. This difference is considered to occur due to difference of optical path route within utilized frequency band. We have rearranged experimental setup to avoid this improper situation, and confirmed that the density in core region measured by both methods is becoming in good agreement.