Damage studies on irradiated tungsten by helium and argon ions in a plasma focus device

Damage of tungsten due to helium and argon ions of a PF device was studied. Tungsten samples were irradiated by 20 shots of the plasma focus device with argon and helium as working gases, separately. The tungsten surface was analyzed by SEM, before and after irradiation. SEM revealed dense blisters with diameters of a few hundred nanometers, on the samples which were irradiated by helium ions, while on the samples irradiated by argon, cracks were developed on the surface. XRD analysis was used for crystallography of tungsten, before and after irradiation. Irradiation by helium and argon affects peak location, peak intensity, FWHM, and spacing of planes, which shows that the crystalline structure of tungsten is affected by irradiation.Characteristics of ion beam of the plasma focus device were calculated by the Lee code. The depth profiles of dpa/shot and ion concentration were calculated using the SRIM code. Using the Lee code, the average fluencies of helium and argon ion beams of the PF device were calculated about 7.9×1014 cm-2 and 0.25×1014 cm2 per shot, respectively. SRIM revealed that the maximum DPA was about 1.7 and 0.17 and occur in the depth of 7 nm and 30 nm for argon and helium, respectively. Also, the maximum concentration occurs in the depth of 20 nm and 40 nm for argon and helium, respectively.