TJ-II:Impurity injection by laser blow-off: influence of main ions charge/mass on impurity confinement and transport

Experimental campaign

2017 Spring

Proposal title

Impurity injection by laser blow-off: influence of main ions charge/mass on impurity confinement and transport

Name and affiliation of proponent

B. López-Miranda 1, B. Zurro 1, M. Martínez 1, E. Hollmann 2, A. Baciero 1, M. Ochando 1, F. Medina 1, K.J. McCarthy 1 and TS and TJ-II Team.//

1 Laboratorio Nacional de Fusión, CIEMAT, Madrid, Spain.

2 University of California, San Diego, La Jolla, CA, USA.

Details of contact person at LNF (if applicable)

B. López-Miranda: belen.lopez@ciemat.es

Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)

Motivation. In previous experiments of impurity confinement in TJ-II plasmas we have investigated the behaviour of impurity confinement with the mass composition of the main ions and with charge/mass of the injected impurities [1]. Now we want to extend our study to He plasmas.

Proposal. Within the present proposal, we plan to inject light and heavy impurities into TJ-II ECRH plasmas by means of laser blow-off. We plan to study the behaviour of impurity confinement with the charge/mass of the main ions on the relaxation of emission of light and heavy impurities injected in TJ-II. For that purpose we want discharges in He and study the impurity confinement as a function of effective mass.

If applicable, International or National funding project or entity

This work was funded by the Spanish “MINECO” under Grant No. ENE2014-56517-R. B.L.M. would like to acknowledge her scholarship, Grant No. BES-2015-075704.

Description of required resources

Required resources:

• Number of plasma discharges or days of operation: We would need at least three operational days: one (compatible with other experiments) to adjust all the variables of the laser blow-off system and two days to perform the experiment.
• Essential diagnostic systems: Main diagnostics will be radiation diagnostics (bolometers, X-rays, VUV spectrometer, etc.) and ECR radiometer data as well as other diagnostics with good time resolution.
• Type of plasmas (heating configuration): We need standard configuration plasmas (100_44_64) with ECRH heating.
• Specific requirements on wall conditioning if any:

1. We want discharges in He in order to study the impurity confinement as a function of effective mass.

2. We need discharges with solely ECRH and good control with constant density along discharges. Lower densities appear to give more stable target plasmas; however, we wish plasma electron densities that are sufficiently high to ensure good Thomson scattering profiling of the target plasma.

• External users: need a local computer account for data access: N
• Any external equipment to be integrated? Provide description and integration needs: N

Preferred dates and degree of flexibility

Preferred dates: (XX-03-2017) We would like to perform the experiment during March 2017.

References

1. ZURRO B., HOLLMANN E., BACIERO A., OCHANDO M.A., MEDINA F., McCARTHY K.J. et al., “Transport studies using laser blow-off injection of low-Z trace impurities injected into the TJ-II stellarator”, Nuclear Fusion 51 (2011) 063015 (9pp).

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