TJ-II: impact of impurities on turbulence: Difference between revisions
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'''Motivation.''' | '''Motivation.''' | ||
In the context of analytical theory, the stabilizing role of impurities on Ion-Temperature-Gradient (ITG) driven instability has been known for decades, see e.g. <ref>R. R. Domínguez and M. N. Rosenbluth, Nuclear Fusion '''29''' 844 (1989).</ref>, where the linear dispersion relation shows that the increase of the impurity concentration has a positive impact on the critical gradient of the toroidal ITG mode and its growth rate. Numerically, and on a quasi-linear fashion, in <ref>R. R. Domínguez and G. M. Staebler, Nuclear Fusion '''33''' 51 (1993).</ref> the benign impact of increasing the effective charge, $Z_{\text{eff}}$, on ITG stability, albeit for the simplified geometry | In the context of analytical theory, the stabilizing role of impurities on Ion-Temperature-Gradient (ITG) driven instability has been known for decades, see e.g. <ref>R. R. Domínguez and M. N. Rosenbluth, Nuclear Fusion '''29''' 844 (1989).</ref>, where the derived linear dispersion relation shows that the increase of the impurity concentration has a positive impact on the critical gradient of the toroidal ITG mode and its growth rate. Numerically, and on a quasi-linear fashion, in <ref>R. R. Domínguez and G. M. Staebler, Nuclear Fusion '''33''' 51 (1993).</ref> the benign impact of increasing the effective charge, $Z_{\text{eff}}$, on ITG stability is demonstrated, albeit for the simplified slab geometry, at the time that the impact is found deleterious for Trapped Electron Modes (TEMs). The interest in these early works and on the question itself about the active role of impurities on the overall turbulence behavior has been brought to the front line of stellarator research by recent experiments in W7-X <ref>R. Lunsford ''et al'' Phys. Plasmas '''28''' 082506 (2021) </ref>. In the reported experimental conclusions, it is highlighted an increase of up to a 30% in the central ion temperature follows the injection of non-trace amounts of Boron. Given the evidence | ||
''' Proposal ''' | ''' Proposal ''' | ||
Revision as of 11:29, 19 January 2022
Experimental campaign
Spring 2022
Proposal title
Impact of impurities on turbulent transport
Name and affiliation of proponent
García-Regaña, J. M., Baciero, A., Calvo, I., Carralero D., Estrada T., González-Jerez A., López-Miranda, B., Medina, F., McCarthy K. J., Ochando, M. A., Thienpondt, H., Velasco, J. L., and the TJ-II team, Laboratorio Nacional de Fusion, CIEMAT (Spain)
Details of contact person at LNF
jose.regana@ciemat.es
Description of the activity
Motivation.
In the context of analytical theory, the stabilizing role of impurities on Ion-Temperature-Gradient (ITG) driven instability has been known for decades, see e.g. [1], where the derived linear dispersion relation shows that the increase of the impurity concentration has a positive impact on the critical gradient of the toroidal ITG mode and its growth rate. Numerically, and on a quasi-linear fashion, in [2] the benign impact of increasing the effective charge, $Z_{\text{eff}}$, on ITG stability is demonstrated, albeit for the simplified slab geometry, at the time that the impact is found deleterious for Trapped Electron Modes (TEMs). The interest in these early works and on the question itself about the active role of impurities on the overall turbulence behavior has been brought to the front line of stellarator research by recent experiments in W7-X [3]. In the reported experimental conclusions, it is highlighted an increase of up to a 30% in the central ion temperature follows the injection of non-trace amounts of Boron. Given the evidence
Proposal
In the present proposal the impact of impurities on the background turbulence will be studied.
International or National funding project or entity
Include funding here (grants, national plans)
Description of required resources
Required resources:
- Number of plasma discharges or days of operation:
- Essential diagnostic systems:
- Type of plasmas (heating configuration):
- Specific requirements on wall conditioning if any:
- External users: need a local computer account for data access: yes/no
- Any external equipment to be integrated? Provide description and integration needs:
Preferred dates and degree of flexibility
Preferred dates: (format dd-mm-yyyy)