Results from the High-Power Helicon Current Drive System at DIII-D

ORAL

Abstract

Heating and current drive by helicon waves, i.e., fast waves in the lower hybrid frequency range, is predicted to be efficient in reactor plasmas. Experiments at DIII-D use a 'comb-line' traveling wave antenna at 476 MHz. Recent upgrades have enabled coupled power levels of > 0.5 MW for pulse lengths of > 2 s. The system was shown to be load-resilient in ELMing H-mode plasmas with no indication of impurities associated with injection. Recent experiments have studied power deposition by seeking a core electron temperature response phase-locked to modulated helicon power. Coherent Te modulations were observed on core ECE channels (rho < 0.4) at a range of modulation frequencies. Comparison shots were acquired with 2nd harmonic X-mode and weakly-absorbed 2nd harmonic O-mode ECH. High-frequency Ion Cyclotron Emission magnetic probes measured nonlinear sidebands near 476 MHz, correlated with spectral peaks at edge ion cyclotron harmonics. In parallel, new diagnostics are coming online, including Doppler back scattering (DBS), a helium beam edge density diagnostic, Doppler-free saturation spectroscopy (DFSS), and a high-frequency phase contrast imaging (PCI).

*Work supported by US DOE under Award(s) DE-FC02-04ER54698, DE-SC0016154, DE-AC05-00OR22725, DE-SC0020284, DE-SC0020649.

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Presenters

  • Shawn X Tang

    • Oak Ridge Assoc Univ
    • General Atomics

Authors

  • Shawn X Tang

    • Oak Ridge Assoc Univ
    • General Atomics

  • Bart G Van Compernolle

    • General Atomics
    • General Atomics - San Diego
    • General Atomics- San Diego

  • Robert I Pinsker

    • General Atomics

  • Jeff B Lestz

    • General Atomics

  • Charles Moeller

    • General Atomics - San Diego
    • General Atomics

  • Craig C Petty

    • General Atomics - San Diego

  • Levi McAllister

    • General Atomics

  • Esteban Bagdy

    • General Atomics

  • Antonio C Torrezan

    • General Atomics

  • Alexandre Dupuy

    • General Atomics

  • A. Nagy

    • Princeton Plasma Physics Laboratory

  • Miklos Porkolab

    • Massachusetts Institute of Technology (MIT)

  • Neal A Crocker

    • University of California, Los Angeles

  • Satyajit Chowdhury

    • University of California, Los Angeles

  • Gilson Ronchi

    • Oak Ridge National Lab

  • Elijah H Martin

    • Oak Ridge National Lab

  • Santiago Vargas Giraldo

    • University of Wisconsin - Madison
    • University of Wisconsin, Madison

  • Aysia Demby

    • University of Wisconsin - Madison

  • Oliver Schmitz

    • University of Wisconsin - Madison

  • Alessandro Marinoni

    • Massachusetts Institute of Technology MIT

  • Christopher C Rost

    • Massachusetts Institute of Technology MIT
    • Massachusetts Institute of Technology

  • Genevieve H DeGrandchamp

    • Lawrence Livermore National Laboratory