Temperature-Enhanced Low-Energy Ion Sputtering of Liquid Tin: Measurements and Modeling

The potential for liquid Sn as a plasma-facing component in advanced thermonuclear fusion reactors and the observation of temperature-enhanced sputtering of Sn under low energy, light ion bombardment motivated further investigation of the temperature-dependent sputtering properties of Sn under various conditions. Experimental measurements using a well-characterized ion beam and a quartz-crystal microbalance (QCM) show that while the sputtering yield of Sn under 1000 eV He+ bombardment at 45° incidence increased from 0.33 +/- 0.14 to 0.80 +/- 0.24 atoms/ion due to increasing the sample temperature from 250°C to 575°C, cases where incident mass or energy were increased did not exhibit temperature dependence. Increasing the incident He+ energy to 2000 eV negated any temperature-dependencies as well as changing the incident species to Ne+ or Ar +. The mechanisms behind temperature enhanced sputtering are not clearly understood, but these data indicate that either the level of energy coupling between incident and target atoms or ion momentum could play a key role. Furthermore, molecular dynamics simulations provide evidence that the kinematics of the system have temperature dependent quantities that differ in the bulk than near ejected atoms. Implications on the use of liquid Sn as a divertor surface are addressed in addition to presentation of data and models.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Nuclear Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Coventry, Matthew David

Contributors dc:contributor

• Ruzic, David N.

• Engineering, Nuclear

Language dc:language

eng

Identifier

(MiAaPQ)AAI3269868

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85910