TJ-II:Real Time lithiatiation of TJII

Experimental campaign

2018 Autumn

Proposal title

Real-Time Lithiation in TJ-II and Ti edge measurements

Name and affiliation of proponent

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Details of contact person at LNF (if applicable)

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

Goal: To implement a method for real time lithiation during plasma shots in TJ-II.

Background: Real time conditioning techniques have a high potential for application to steady state plasma operation (next generation of SC devices). Boronization by powder dropping I W7X ad UUG and lithiation by Li injector in NSTX, EAST, etc…, following the successful experience of the DOLLOP technique in TFTR. The aim of the proposal in TJ-II is to check if the full wall lithiation performed routinely can be substituted by short injection during plasma operation, so that the build up of flaking Li films can be avoided.

Description: The NdYag laser used for Blow Off experiments will be focussed into the vacuum vessel opposite to it. The local power density will be controlled by a lens, in order to produce the right dose of Li compatible with normal plasma operation, similar to those induced by pellet injection now. Once this is achieved, a devoted Li source will be located near the wall to have a reproducible supply of Li. Eventually, a real Dollop injector will be developed. The transport of the injected Li ions will be monitored at a given toroidal distance from the injection through its emission and the time trace will be used to deduce the kinetic energy at this location. A simple thermalization model will be used to deduce the Ti value of the plasma.The resulting Ti value will be compared with other diagnostics (RFA, Doppler, NPA...)

Requirements. High density plasmas (NBI) seem better suited due to a lower perturbation of the line density by the injected Li, although power balance considerations may suggest otherwise (ECRH). Frequent entrances to the TJII hall are foreseen at the beginning. Characteristic signatures of FW state (recycling, density control, impurities , radiation,..) will be monitored.

If applicable, International or National funding project or entity

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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

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References

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