L-H threshold database: Status and Plans

J.W. Hughes, J. Stillerman, MIT PSFCY. Martin, CRPP-EPFL

P. Gohil, GAD. McDonald, JET-EFDA

Meeting of the ITPA Pedestal and Transport & Confinement Topical GroupsPrinceton, NJ

6 October 2009

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L-H threshold database is changing hands, expanding

• MIT is preparing to administer the L-H threshold database– Server operational and ready for import of existing database– Y. Martin is ready to export – Supported by PSFC computing personnel– Accessible to ITPA participants– Community usage, openness encouraged

• Reduced role of centralized administration• Simple password authentication for ease of access (server will be outside

facility firewall)• Development of APIs to allow ease of data extraction, insertion for individual

users

– Nightly backups (kept inside firewall) plus version archiving following publications

• Two stage development– Existing scalar power threshold database, on an SQL server– Profile data, stored in standardized MDSplus tree structures (analogous

to existing profile databases used by Pedestal, DIV/SOL groups)

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How we got here

• Transfer first discussed at 10/08 ITPA meeting

• At same meeting, L-H transition working group was formed, with contacts at many facilities– AUG: F. Ryter

– C-Mod: J. Hughes

– DIII-D: P. Gohil

– JET: Y. Andrews/D. McDonald

– JT-60U: K. Kamiya

– MAST: H. Meyer/M. Valovic

– NSTX: R. Maingi

– TCV: Y. Martin

– TUMAN-3M: S. Lebedev

• Generally agreed that a profile database would provide greater physics content for transition studies– Continued discussions among

working group members attending spring T&C meeting

– General discussion session at the spring pedestal meeting

• This meeting: Agree on purpose, form of profile database– Input from both

experimentalists and modelers is desired

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A goal-oriented threshold DB

• DB effort will only be effective if clear goals are established, e.g.:

• Profile data for reducing the uncertainty in Pthresh prediction– Eliminate the “black magic” of hidden variables– In individual devices: Identification of important local parameters

as part of global parameter scans– Common threshold conditions across devices with joint

experiments defined• Profile data for model testing

– A potential repository for well-diagnosed discharges– Profile evolution before and across the L-H transition– Turbulence characteristics?

• Profile data for predictive capabilites (ITER)– Short term: 0D (and some 1D?) approach based on JEX results– Long term: simulations based on validated models

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Ideas for profile database development

• Participants in database effort determine composition of profile DB

• Content driven by priorities, key goals of researchers (see previous slide)

• Data sets should be sufficient to provide useful profiles, but not so extensive as to discourage participation

• A possible model is a tiered data set– Tier 1. Global parameters: <ne>, BT, IP, etc. (plus d/dt of each)– Tier 2. Essential profiles: ne,i, Te,i, vi, vi et al.– Tier 3. Profiles requiring analysis: Poh, Paux, jBS et al.– Tier 4. Advanced profile measurements: Prad, n0, flucts. et al.

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How to proceed

• The pedestal profile database is an excellent starting point– Motivation for its development was similar– Much of the work has already been done– Can be merged with existing L-H db parameters

• Compelling features– Provides a uniform data structure built on MDSplus trees – Upwards compatible with the (core) confinement profile DB– Contains branches for data of varied

sophistication: .ZEROD:, .ONED:, .TWOD:, .ONEDTR:, .TWODTR:, etc.

– Contains mechanism for timing with respect to plasma events (e.g. L-H transition time, H-L transition time, sawteeth)

– .DIV branch provides inputs for SOL/divertor modeling • Downside: Trees don’t populate themselves. Work is

required of contributors.

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Suggested plan of attack

• Build on existing nodes of confinement and pedestal profile trees

• Identify additional measurements which should be included (discussion among interested parties to follow)

• Identify a suitable joint experiment to motivate initial deposits into the DB

• Use DB to facilitate analysis/modeling for ITER research, publications

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Discussion

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Discussion

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Discussion

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Discussion