In-Situ Analysis of Dispersion Strengthened Tungsten Alloys and the Effect of Dispersoid Population on the Areal Density of Helium Bubble Nucleation
Open Access
Author:
Lambert, Evan
Area of Honors:
Nuclear Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Jean Paul Allain, Thesis Supervisor Elia Merzari, Thesis Honors Advisor
Keywords:
fusion plasma ITER Tungsten Helium PFC
Abstract:
Nuclear fusion has long been a proposed form of energy creation; however, it always has its shortcomings whether that be in confinement technology, magnetic technology, etc. In 2025, the ITER tokamak will begin operation as the world’s largest experiment in nuclear fusion. This massive machine undergoes extraordinarily harsh conditions of high heat flux and high particle flux. A region within the reactor that experiences a particularly high particle flux is called the divertor. The divertor of ITER will be made mostly of stainless steel with a thin tungsten coating to assist in protection of high energy ions. The properties of pure tungsten are desirable for implementation into the harsh environment inside of a tokamak; however, helium atoms at high fluxes are known to nucleate as bubbles within the tungsten which in turn, burst, damaging the material and creating less desirable physical properties. Advanced tungsten alloys such as dispersion strengthened tungsten have been proposed as a means to combat or slow down the rate of helium bubble nucleation. In this work, a 5-weight percent tantalum carbide dispersion strengthened tungsten was analyzed with an in-situ TEM facility dosed with a fluence of 2 keV helium ions. 4 regions were selected and the areal helium bubble density was counted as a function of fluence. It was found that the presence of the carbide dispersoids overall lowers the density of helium bubbles while the presence of bubbles in the dispersoids themselves is nonexistent.