DBS

Contacts: Unattributed

Short Description

Multi-channel Doppler back-scattering (DBS) diagnostic analysis

Keywords

DBS, Flow Velocity, Turbulence, Density Fluctuations

Long Description

The OMFIT-DBS module provides an integrated approach to analyzing data from the UCLA multi-channel Doppler back-scattering (DBS) diagnostics installed on the DIII-D and MAST(U) tokamaks. On DIII-D, DBS data from systems located at the 60-deg and 240-deg (toroidal) ports are available for analysis. For older DIII-D discharges, legacy (e.g. the W-band and “DBS-5”) systems are also available. On MAST(U), DBS data from the V-band and Q-band systems are available for analysis.

Experimental DBS data analysis is generally performed over multiple times slices within a single plasma discharge. Labor-intensive frequency-domain analysis (fitting Doppler-shifted spectral components) is possible with the DBS_SPECTROGRAM_GUI. Ray-tracing (using GENRAY) or beam-tracing (using Scotty or TORBEAM) is used to calculate wave trajectories and probed-wavenumbers. Outputs of DBS analysis include: amplitude of density fluctuations, the DBS probed radial location(s) and probed wavenumber(s), flow velocity of turbulent structures, radial electric field, E_r, and omega_E=E_r/RBp.

Typical workflows

• Fetch raw DBS data

• (Optional) ELM filtering

• DBS spectrum analysis and visualization

  • Doppler shift calculation

  • Spectral power calculation

• GENRAY/SCOTTY/TORBEAM setup with magnetic equilibria (gEQDSK files from EFIT) and profiles (supported formats include: OMFITprofile, pFiles, input.gacode, etc…)

• Run Ray/Beam tracing with DBS launch parameters

• Calculate derived quantities and plot

• Plan for experiments (ray tracing angle-scans, wavenumber targeting)

Supported devices

• DIII-D

• MAST

• NSTX

Tutorials

• Google docs tutorial

Citing the DBS module

If you use the OMFIT-DBS module in your analysis consider citing the following paper, .. code-block:: none

@article{DBS2025,

author = {Q. T. Pratt, T. L. Rhodes and T. A. Carter}, title = {Doppler Backscattering Data Analysis and Integrated Modeling with OMFIT}, journal = {Fusion Science and Technology}, volume = {0}, number = {0}, pages = {1–23}, year = {2025}, publisher = {American Nuclear Society}, doi = {10.1080/15361055.2025.2452128}, URL = {https://doi.org/10.1080/15361055.2025.2452128}, eprint = {https://doi.org/10.1080/15361055.2025.2452128}

}

Relevant publications

• Peebles, W. A., et al. “A novel, multichannel, comb-frequency Doppler backscatter system.” Review of Scientific Instruments 81.10 (2010): 10D902.

• Rhodes, T. L., et al. “Optimized quasi-optical cross-polarization scattering system for the measurement of magnetic turbulence on the DIII-D tokamak.” Review of Scientific Instruments 89.10 (2018): 10H107.

Classes

• omfit_classes.omfit_base.OMFITcollection()

• omfit_classes.omfit_csv.OMFITcsv()

• omfit_classes.omfit_elm.OMFITelm()

• omfit_classes.omfit_eqdsk.OMFITgeqdsk()

• omfit_classes.omfit_genray.OMFITgenray()

• omfit_classes.omfit_google_sheet.OMFITgoogleSheet()

• omfit_classes.omfit_mds.OMFITmdsValue()

• omfit_classes.omfit_mds.OMFITmds()

• omfit_classes.omfit_profiles.OMFITprofiles()

• omfit_classes.omfit_thomson.OMFITthomson()

Contributors

List of contributors sorted by number of lines authored:

24297 Quinn Pratt
  644 Stephen Storment
  120 Clive Michael
   39 kgage
   15 Torrin Bechtel
   12 Will DeShazer
   11 Orso Meneghini
    2 Bhavin Patel
    1 Fusion Bot

Submodules

• GENRAY

Users

List of usernames sorted by number of module imports: macwant, prattq, dambaj, cmichael, hongrongjie, zeng, trhodes, chowdhurys, ashtonkeya, callahank, pshi, storments, fh3490, yuguanying, cn8435, yeoha, baradakk, zm2756, wangg, gagek, bpatel2, wangy, crocker, jiahongray, farreh, ernst, kg7356, rhodes, verao, ashourvana, hallchenv, kn7062, dk4283, tmacwan2, lyonss, ravi, simeonnachmannn, smithsp, kimsang, wudonggui, yangseongmoo, happelt, jruizru, liud, niraje, sliefj, traversop, vchen, hanxiang, houshman, khabanovf, kobayashi, kq9832, lizeyu, meneghini, ncrocker, schmitzl, asladkom, degrandchampg, dingsiye, fernandezp, grierson, haskeysr, krietedm, liul, ly8590, mcclenaghanj, michaelc, ml3806, peebles, stewarts, weixishuo, xchen