- By:
- Caughman, John B; Goulding, Richard H; Biewer, Theodore M; Bigelow, Timothy S; Beers, Clyde J; Campbell, Ian H; Caneses Marin, Juan F; Diem, Stephanie J; Donovan, David C; Isler, Ralph C; Fehling, Daniel T; Fadnek, Andrew ; Martin, Elijah H; Parish, Chad M; Rapp, Juergen ; Flynn, Holly B; Shaw, Guinevere C; Showers, Melissa A; Wang, Kun
- Journal Name:
- Journal of Vacuum Science & Technology A
- Page Number:
- 9223372036854775807
- Volume:
- 35
- Issue Number:
- 3
- Publication Date:
- June 5, 2017
- View DOI Listing:
- https://doi.org/10.1116/1.4982664
Abstract
Plasma facing materials in the divertor of a magnetic fusion reactor will have to tolerate steady-state plasma heat fluxes in the range of 10 MW/m2 for ~107 sec, in addition to fusion neutron fluences, which can damage the plasma facing materials to high displacements per atom (dpa) of ~50 dpa . Material solutions needed for the plasma facing components are yet to be developed and tested. The Materials Plasma Exposure eXperiment (MPEX) is a newly proposed steady state linear plasma device that is designed to deliver the necessary plasma heat flux to a target for this material testing, including the capability to expose a-priori neutron damaged material samples to those plasmas. The requirements of the plasma source needed to deliver this plasma heat flux are being developed on the Proto-MPEX device, which is a linear high-intensity radio frequency (RF) plasma source that combines a high-density helicon plasma generator with electron and ion heating sections. It is being used to study the physics of heating over-dense plasmas in a linear configuration. The helicon plasma is operated at 13.56 MHz with RF power levels up to 120 kW. Microwaves at 28 GHz (~30 kW) are coupled to the electrons in the over-dense helicon plasma via Electron Bernstein Waves (EBW), and ion cyclotron heating at 7-9 MHz (~30 kW) is via a magnetic beach approach. High plasma densities >6x1019/m3 have been produced in deuterium, with electron temperatures that can range from 2 to >10 eV. Operation with on-axis magnetic field strengths between 0.6 and 1.4 T is typical. The plasma heat flux delivered to a target can be > 10 MW/m2, depending on the operating conditions.
