Download or read book Morphology Changes Due to Energetic Helium Ion Irradiation of Tungsten Surfaces at High Temperatures written by Karla Brittany Hall and published by . This book was released on 2019 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Materials Irradiation Experiment (MITE-E) at the University of Wisconsin-Madison in the Inertial Electrostatic Confinement Laboratory was used to simulate helium ion (He+) irradiation of tungsten at fusion reactor relevant ion fluences and temperatures. Single and polycrystalline tungsten (SCW and PCW) samples were irradiated with 30-55 keV He+ at normal incidence with fluences of 3x1017 to 1019 He+/cm2 at temperatures from 500-900 oC. Post-irradiation analysis of the samples irradiated in the MITE-E device revealed several unique surface morphologies when the ion energy, temperature, and fluence were varied. Surface erosion due to energetic He+ irradiation was determined by mass loss measurements of samples pre- and post-irradiation. Past studies in the MITE-E revealed a surface orientation near {001} on PCW had considerably less erosion from He+ irradiation than surrounding grains Morphology development and mass loss measurements on [110] and [100] SCW revealed that the [100] crystal orientation lead to decreased surface erosion below 10^18 He+/cm2. Simulating what a fusion reactor component would likely experience, a sequentially increasing and decreasing multi-energy He+ irradiation on PCW was explored. Samples irradiated with increasing and decreasing multi-energy (35, 45, and 55 keV) He+ showed more surface damage than samples irradiated with mono-energetic (30 keV) He+. However, the multi-energy ion irradiated samples had less mass loss than the mono-energetic ion irradiated samples under similar parameters. Varying the temperature of samples under mono-energetic and multi-energy He+ irradiation at the same fluence caused an increase in mass loss as the temperature was decreased. The amount of mass loss and morphologies that developed on all samples point to He+ as a contributing mechanism in the undesired creation of W dust in a fusion reactor.