ORNL/TM-2018/895 Summary of RF Technology Program Activities October 2013 – September 2017 R. H. Goulding E. H. Martin G. L. Bell J. B. O. Caughman Support of National RF Research and Development Field Work Proposal ERAT560 June 26, 2018 G. L. Bell, Principal Investigator Barry Sullivan, Federal Program Manager Office of Fusion Energy Sciences Approved for public release. Distribution is unlimited. DOCUMENT AVAILABILITY Reports produced after January 1, 1996, are generally available free via US Department of Energy (DOE) SciTech Connect. 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Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. ORNL/TM-2018/895 Fusion and Materials for Nuclear Systems SUMMARY OF RF TECHNOLOGY PROGRAM ACTIVITIES R. H. Goulding E. H. Martin G. L. Bell J. B. O. Caughman Date Published: June 18, 2018 Prepared by OAK RIDGE NATIONAL LABORATORY Oak Ridge, TN 37831-6283 managed by UT-BATTELLE, LLC for the US DEPARTMENT OF ENERGY under contract DE-AC05-00OR22725 CONTENTS ACRONYMS ...............................................................................................................................................vii ABSTRACT ...................................................................................................................................................1 1. BUDGET SUMMARY AND JUSTIFICATION .................................................................................2 2. PROGRAM SUMMARY.......................................................................................................................3 2.1 Doppler-Free Saturation Spectroscopy at ORNL.....................................................................3 2.2 Lower Hybrid Wave Electrical Field Mesurements on Alcator C-Mod.................................7 2.3 Electron Cyclotron Wave Electric Field Measurements on DIII-D........................................8 2.4 Proto-MPEX.................................................................................................................................8 2.4.1 Background................................................................................................................................8 2.4.2 Selected Results .........................................................................................................................9 2.4.3 Status of Base-Program Goals and Tasks Related to Proto-MPEX.........................................10 2.4.4 Future Work.............................................................................................................................11 2.5 RF Sheath Interaction Measusrements....................................................................................12 2.6 ITER Ion Cyclotron Transmission Line and Matching System............................................12 2.6.1 Background..............................................................................................................................12 2.6.2 Selected Results .......................................................................................................................13 2.6.3 Status of Base-Program Goals and Tasks Related to ITER Ion Cyclotron Testing.................13 2.7 Other Activities ..........................................................................................................................15 2.8 References (cited in Program Narrative).................................................................................15 3. KEY PERSONNEL.............................................................................................................................16 4. PRODUCTS ........................................................................................................................................21 4.1 Journal Articles..........................................................................................................................21 4.2 Abstracts/Presentations.............................................................................................................22 4.3 Proceedings.................................................................................................................................25 4.4 Other (US ITER Reports) .........................................................................................................25 5. FACILITIES, EQUIPMENT, AND OTHER RESOURCES ...........................................................26 iii iv LIST OF FIGURES Figure 1. (a) CAD drawing of upgraded experimental test stand, magnetic field lines are shown in red...................4 Figure 2. (a) Image of the RF electrode after assembly and (b) in operation..............................................................5 Figure 3. H (a) Passive OES spectrum (black) and DFSS spectrum (red) measured under 0 V/cm and 875 Gauss. ..........................................................................................................................................................6 Figure 4. DFSS optics associated with the (a) pump and (b) probe beams..................................................6 Figure 5. (a) DFSS based magnetic field measurements as a function of magnetic field coil current.........6 Figure 6. 3D full-wave COMSOL simulation of 퐸퐿퐻 for C-Mod discharge 1160818010...........................7 Figure 7. Direction of 퐸퐿퐻 averaged over net LH power as a function of the white highlighted vertical (left) and horizontal (right) locations of Figure 6.........................................................................................7 Figure 8. Fourier transform of time averaged Dβ spectral data obtained during our proof of principal ex- periment at DIII-D........................................................................................................................................8 Figure 9. Proto-MPEX Layout and axial magnetic field strength profile.xy. ..............................................9 Figure 10. Power traces for FRT-86 (helicon, red), FRT-85 (ICH, blue), and 28 GHz Gyrotron (EBW, magenta) for October 2017 milestone shotxy. ...........................................................................................10 Figure 11. Comparison of a) Plasma density, and b) electron temperature measured with double Langmuir probe with (solid blue lines) and without (dashed red lines) mode jump at “Probe C” location in Fig. 9.10 Figure 12. a) Electron temperature and b) plasma density measured with (red lines) and without (black line) EBW heating by Thomson scattering at “Probe A” location in Figure 9. .........................................10 Figure 13. Comparison of ion temperature measured with helicon alone, helicon+ICH, and helicon+ICH + EBW measured by Ar II line broadening................................................................................................10 Figure 14. a) View looking into ICH antenna vacuum feedthrough from opposite port, and b) view of antenna installed in chamber. .....................................................................................................................11 Figure 15. FRT-86 HV power supply replacement vacuum contactors....................................................................11 Figure 16. FRT-86 Final Power Amplifier (FPA) output tuning circuit. Capacitors, white cooling water tubing, and red cooling water hoses were replaced........................................................................................................................11 Figure 17. Helicon 200 kW combiner network............................................................................................11 Figure 18. The change in the IEDF on a magnetic field line connected to the powered electrode............12 Figure 19. SRA transmission line sections.................................................................................................14 v LIST OF FIGURES (CONT'D) Figure 20. Voltage vs. time for four 3600s pulses, followed by 0.1s pulses at voltages up to ~ 85 kV...14 Figure 21. 6 MW power splitter................................................................................................................14