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Title: RF Sheath-Enhanced Plasma Surface Interaction Studies using Beryllium Optical Emission Spectroscopy in JET ITER-Like Wall

Abstract

A dedicated study on JET-ILW, deploying two types of ICRH antennas and spectroscopic observation spots at two outboard, beryllium limiters, has provided insight on long-range (up to 6m) RFenhanced plasma-surface interactions (RF-PSI) due to near-antenna electric fields. To aid in the interpretation of optical emission measurements of these effects, the antenna near-fields are computed using the TOPICA code, specifically run for the ITER-like antenna (ILA); similar modelling already existed for the standard JET antennas (A2). In the experiment, both antennas were operated in current drive mode, as RF-PSI tends to be higher in this phasing and at similar power (∼0.5 MW). When sweeping the edge magnetic field pitch angle, peaked RF-PSI effects, in the form of 2-4 fold increase in the local Be source,are consistently measured with the observation spots magnetically connect to regions of TOPICAL-calculated high near-fields, particularly at the near-antenna limiters. It is also found that similar RF-PSI effects are produced by the two types of antenna on similarly distant limiters. Although this mapping of calculated near-fields to enhanced RF-PSI gives only qualitative interpretion of the data, the present dataset is expected to provide a sound experimental basis for emerging RF sheath simulation model validation.

Authors:
 [1]; ORCiD logo [2];  [3];  [4];  [5];  [6]; ORCiD logo [2];  [7];  [8]; ORCiD logo [2];  [9];  [9];  [4]
  1. Fusion for Energy (F4E), Barcelona, Spain
  2. ORNL
  3. French Atomic Energy Commission (CEA)
  4. Ecole Royale Militaire, Brussels Belgium
  5. Max-Planck-Institut fur Plasmaphysik, EURATOM Association, Garching, Germany
  6. Culham Centre for Fusion Energy (CCFE), Abingdon, UK
  7. EURATOM / UKAEA, UK
  8. Association EURATOM-CCFE, Abingdon, UK
  9. ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1423084
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 22nd Radiofrequency Power in Plasmas Topical Conference (RFPPC 2017) - Aix-en-Provence, , France - 5/30/2017 12:00:00 AM-6/2/2017 12:00:00 AM
Country of Publication:
United States
Language:
English

Citation Formats

Agarici, G., Klepper, C Christopher, Colas, L., Krivska, Alena, Bobkov, V., Jacquet, P., Delabie, Ephrem G., Giroud, C., Kirov, K K., Lasa Esquisabel, Ane, Lerche, E., Dumortier, P., and Durodie, Frederic. RF Sheath-Enhanced Plasma Surface Interaction Studies using Beryllium Optical Emission Spectroscopy in JET ITER-Like Wall. United States: N. p., 2017. Web.
Agarici, G., Klepper, C Christopher, Colas, L., Krivska, Alena, Bobkov, V., Jacquet, P., Delabie, Ephrem G., Giroud, C., Kirov, K K., Lasa Esquisabel, Ane, Lerche, E., Dumortier, P., & Durodie, Frederic. RF Sheath-Enhanced Plasma Surface Interaction Studies using Beryllium Optical Emission Spectroscopy in JET ITER-Like Wall. United States.
Agarici, G., Klepper, C Christopher, Colas, L., Krivska, Alena, Bobkov, V., Jacquet, P., Delabie, Ephrem G., Giroud, C., Kirov, K K., Lasa Esquisabel, Ane, Lerche, E., Dumortier, P., and Durodie, Frederic. Sun . "RF Sheath-Enhanced Plasma Surface Interaction Studies using Beryllium Optical Emission Spectroscopy in JET ITER-Like Wall". United States. doi:. https://www.osti.gov/servlets/purl/1423084.
@article{osti_1423084,
title = {RF Sheath-Enhanced Plasma Surface Interaction Studies using Beryllium Optical Emission Spectroscopy in JET ITER-Like Wall},
author = {Agarici, G. and Klepper, C Christopher and Colas, L. and Krivska, Alena and Bobkov, V. and Jacquet, P. and Delabie, Ephrem G. and Giroud, C. and Kirov, K K. and Lasa Esquisabel, Ane and Lerche, E. and Dumortier, P. and Durodie, Frederic},
abstractNote = {A dedicated study on JET-ILW, deploying two types of ICRH antennas and spectroscopic observation spots at two outboard, beryllium limiters, has provided insight on long-range (up to 6m) RFenhanced plasma-surface interactions (RF-PSI) due to near-antenna electric fields. To aid in the interpretation of optical emission measurements of these effects, the antenna near-fields are computed using the TOPICA code, specifically run for the ITER-like antenna (ILA); similar modelling already existed for the standard JET antennas (A2). In the experiment, both antennas were operated in current drive mode, as RF-PSI tends to be higher in this phasing and at similar power (∼0.5 MW). When sweeping the edge magnetic field pitch angle, peaked RF-PSI effects, in the form of 2-4 fold increase in the local Be source,are consistently measured with the observation spots magnetically connect to regions of TOPICAL-calculated high near-fields, particularly at the near-antenna limiters. It is also found that similar RF-PSI effects are produced by the two types of antenna on similarly distant limiters. Although this mapping of calculated near-fields to enhanced RF-PSI gives only qualitative interpretion of the data, the present dataset is expected to provide a sound experimental basis for emerging RF sheath simulation model validation.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2017},
month = {Sun Oct 01 00:00:00 EDT 2017}
}

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