Radiation damage assessment of atomically thin membranes

This thesis investigates the methodologies and results of gas transport across atomically thin membranes, which are relevant to reducing Tritium inventory in fusion reactors by separating Helium from the plasma exhaust stream. A novel experimental apparatus and set-up is devised to measure the gas transport rate across a membrane by containing a pool of liquid water that evaporates over time and passes through the membrane interface to the environment. This device minimizes flow resistance on both sides, allowing for membrane resistance changes to be appropriately assessed. This apparatus also measures less than 5 % error between trials on the same membrane, which can be improved with more data collection for each transport measurement. Graphene is transferred onto high pore density polyimide (-50 nm pore diameter, 6E9 pores cm⁻²) and is imaged with a scanning electron microscope (SEM) to assess graphene transfer fidelity. It is found that graphene coverage (defined as the fraction of the polyimide covered by visibly intact graphene) for samples can be as high as 98% using the transfer method explained in this work. The resulting membranes are irradiated with varying levels of Gallium ion radiation in a focused ion beam machine. It is found that irradiating the sample with ion beam settings of 8 keV acceleration voltage and a dosage of 2.53E+13 Gallium ions cm 2 causes no noticeable change in membrane performance of water vapor transport. Future work will include irradiating the sample at higher dosages and assessing membrane performance while correlating these dosages to what is expected in a fusion reactor setting.

Name thesis:degree_name

Bachelor

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2020

Author dc:creator

• Parks, Sean M.

Advisor dc:contributor.advisor

• Rohit Kamik.

• Mechanical Engineering.

Statement dc:rights

• MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1721.1/145218

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/145218