AVS 63rd International Symposium & Exhibition
    Plasma Science and Technology Wednesday Sessions
       Session PS-WeM

Invited Paper PS-WeM10
Plasma Source Development for Fusion Relevant Material Testing

Wednesday, November 9, 2016, 11:00 am, Room 104B

Session: Plasma Sources and Novel Mechanisms for Generating Plasmas
Presenter: John Caughman, Oak Ridge National Laboratory
Authors: J.B.O. Caughman, Oak Ridge National Laboratory
R.H. Goulding, Oak Ridge National Laboratory
T.M. Biewer, Oak Ridge National Laboratory
T.S. Bigelow, Oak Ridge National Laboratory
I.H. Campbell, Oak Ridge National Laboratory
S.J. Diem, Oak Ridge National Laboratory
A. Fadnek, Oak Ridge National Laboratory
D.T. Fehling, Oak Ridge National Laboratory
D.L. Green, Oak Ridge National Laboratory
C.H. Lau, Oak Ridge National Laboratory
E.H. Martin, Oak Ridge National Laboratory
P.V. Pesavento, Oak Ridge National Laboratory
J. Rapp, Oak Ridge National Laboratory
H.B. Ray, University of Tennessee
G.C. Shaw, University of Tennessee
M.A. Showers, University of Tennessee
P. Piotrowicz, University of Illinois at Urbana-Champaign
D.N. Ruzic, University of Illinois at Urbana-Champaign
G.-N. Luo, Chinese Academy of Sciences
Correspondent: Click to Email
Plasma facing materials in a magnetic fusion reactor have to tolerate plasma heat fluxes of 10 MW/m2. The Prototype Materials Plasma Experiment (Proto-MPEX) 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 with the goal of producing up to 10 MW/m2 of plasma heat flux on a target. The helicon plasma is operated at 13.56 MHz with RF power levels up to 100 kW. Microwaves at 28 GHz (~150 kW) are coupled to the electrons in the over-dense helicon plasma via Electron Bernstein Waves (EBW), and ion cyclotron heating (~30 kW) is via a magnetic beach approach. Plasma diagnostics include Thomson Scattering and a retarding field energy analyzer near the target, while a microwave interferometer and double-Langmuir probes are used to determine plasma parameters elsewhere in the system. Filterscopes are being used to measure D-alpha emission and He line ratios at multiple locations within the device, and IR cameras image the target plates to determine heat deposition both upstream and downstream of the helicon source region. High plasma densities have been produced in helium (>3x1019/m3) and deuterium (>2x1019/m3), 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. Plasma parameters vary depending on the operating pressure/gas flow, and skimmer plates are used to try to control the neutral pressure in the device. The ion energy distribution varies radially/axially and is related to changes in the electron temperature and antenna coupling conditions. The helicon antenna coupling is being model with the COMSOL and VORPAL programs to help explain and guide operations. Details of the experimental results and operating parameters related to ion energies and delivered plasma heat flux will be presented.