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Modelling of Neutron Markers for the COMPASS Upgrade Tokamak and Generation of Synthetic Neutron Spectra


In the future COMPASS Upgrade (Vondracek et al. in Fusion Eng Des 169:112490,, 2021) tokamak (\(R_0 = 0.894\, \mathrm {m}\), \(B_t \sim 5\, \mathrm {T}\)), three distinct types of edge transport barrier are anticipated: ELMy H-mode, EDA H-mode and I-mode. The main auxiliary heating system used to access H-mode will be Neutral Beam Injection (NBI) power. The NBI will have a nominal injection energy of \(80\,\mathrm {keV}\) at a maximum injection radius \(R_{\mathrm {tan}} = 0.6\, \mathrm {m}\). A significant neutron yield will occur from the interaction of the beam with the plasma background. Using our orbit-following code EBdyna (Jaulmes et al. in Nucl Fusion 61, 046012,, 2021), we calculate the trajectories of the NBI ions during the complete thermalization process, calculate the amount of NBI ions losses and evaluate the neutron rate in steady state from the beam–plasma and beam–beam interaction. Combining it with the thermal yield, we can derive detailed synthetic spectrogram of the energy distribution of the neutrons. The markers can be further used to provide synthetic neutron spectrometer diagnostics data. Due to the reduction of the simulated neutron count seen by the detectors when the peaking of the neutron source is lower, we anticipate the need for absolute-calibration in order to recover quantitative results.

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  1. P. Vondracek et al., Preliminary design of the compass upgrade tokamak. Fusion Eng. Des. 169, 112490 (2021).

    Article  Google Scholar 

  2. F. Jaulmes et al., Modelling of charge-exchange induced nbi losses in the compass upgrade tokamak. Nucl. Fusion 61, 046012 (2021).

    ADS  Article  Google Scholar 

  3. J. Bielecki et al., Neutron diagnostics for tokamak plasma: from a plasma diagnostician perspective. J. Fusion Energ 38, 386 (2019).

    Article  Google Scholar 

  4. V. Weinzettl et al., Constraints on conceptual design of diagnostics for the high magnetic field compass-u tokamak with hot walls. Plasma Phys. 146(Part B), 1703 (2017).

    Article  Google Scholar 

  5. J.F. Artaud et al., Metis: a fast integrated tokamak modelling tool for scenario design. Nucl. Fusion 58, 105001 (2018).

    ADS  Article  Google Scholar 

  6. E.A. Tolman et al., Influence of high magnetic field on access to stationary h-modes and pedestal characteristics in alcator c-mod. Nucl. Fusion 58, 046004 (2000).

    ADS  Article  Google Scholar 

  7. A.E. Hubbard et al., Physics and performance of the i-mode regime over an expanded operating space on alcator c-mod. Nucl. Fusion 57, 126039 (2017).

    ADS  Article  Google Scholar 

  8. Y.R. Martin et al., Power requirement for accessing the h-mode in iter. Phys. Conf. Ser. 123, 012033 (2008).

    Article  Google Scholar 

  9. F. Ryter et al., Experimental evidence for the key role of the ion heat channel in the physics of the l-h transition. Nucl. Fusion 54, 083003 (2014).

    ADS  Article  Google Scholar 

  10. J.R. Walk, in Pedestal Structure and Stability in High-Performance Plasmas on Alcator c-mod. Ph.D. thesis (2014)

  11. ITER, Physics Guidelines Annex A.1, 19–101071301 (2002)

  12. J.W. Hughes, H-mode pedestal and l-h transition studies on alcator c-mod. Fusion Sci. Technol. 51(3), 317–341 (2007).

    Article  Google Scholar 

  13. J.D. Callen, in Draft Material for Fundamentals of Plasma Physics book. (2006)

  14. H.-S. Bosch, M. Hale, Improved formulas for fusion cross-sections and thermal reactivities. Nucl. Fusion 32, 611 (1992).

    ADS  Article  Google Scholar 

  15. H. Brysk, Fusion neutron energies and spectra. Plasma Phys. 15, 611 (1973).

    ADS  Article  Google Scholar 

  16. Ž Štancar et al., Multiphysics approach to plasma neutron source modelling at the jet tokamak. Nucl. Fusion 59, 096020 (2019).

    ADS  Article  Google Scholar 

  17. G. Cunningham, High performance plasma vertical position control system for upgraded mast. Fusion Eng. Des. 88, 3238 (2013).

    Article  Google Scholar 

Download references


This work has been carried out within the framework of the project COMPASS-U: Tokamak for cutting-edge fusion research (No. CZ.02.1.01/0.0/0.0/16_019/0000768) and co-funded from European structural and investment funds. This work was supported by the Project PAN-20-12 “Neutron emission and transport at the COMPASS-U tokamak” of Investigators E. Macúšová and J. Bielecki. This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic through the e-INFRA CZ (ID:90140). Simulations data were generated at the IT4I Barbora computational cluster. Derived data supporting the findings of this study are available from the corresponding author upon request

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Correspondence to Fabien Jaulmes.

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Jaulmes, F., Ficker, O., Weinzettl, V. et al. Modelling of Neutron Markers for the COMPASS Upgrade Tokamak and Generation of Synthetic Neutron Spectra. J Fusion Energ 41, 16 (2022).

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  • NBI
  • Neutrons
  • Neutron detector
  • COMPASS upgrade