Proceedings of ITC/ISHW2007 P1-037

Status of the International Stellarator/Heliotron Profile Database
The ISHPDB Collaboration
A. Dinklage , E. Ascasibar , C.D. Beidlera, R. Brakela, R. Burhenna, F. Castejonb, T. Estradab,
H. Funabac, Y. Fenga, J. Geigera, J.H. Harrisd,e, C. Hidalgob, K. Idac, M. Kobayashic, R. Königa,
G. Kühnera, A. Kusa, D. Lopez Brunab, H. Maaßberga, K. McCarthyb, D. Mikkelsenf, T. Mizuuchig,
N. Nakajimac, R. Preussa, S. Sakakibarac, F. Sanog, F. Sardeib, U. Strothh, Y. Suzukic,
J. Talmadgei, H. Thomsena, Yu. A. Turkin a, B. Ph. Van Milligenb, K.Y. Watanabec, A. Wellera,
A. Wernera, R. Wolfa, H. Yamadac, M. Yokoyamac
a,*

a

b

Max-Planck-Institut für Plasmaphysik, EURATOM Association, Greifswald, GermanybLaboratorio Nacional de Fusión, Asociación Euratom/CIEMAT, Madrid, SpaincNational Institute for Fusion Science,322-6 Oroshi-cho, Toki 509-5292, Japand
Oak Ridge National Laboratory, USAeAustralian National University, Canberra, AustraliafPrinceton Plasma Physics Laboratory, Princeton, USAg
Kyoto University, Kyoto, JapanhInstitut für Plasmaforschung, Universität Stuttgart, GermanyiUniversity of Wisconsin, USA

The International Stellarator/Heliotron Profile Database (ISHPDB) is a community effort aiming at a concise
documentation of experimental data and modeling of stellarator reactor relevant issues. ISHPDB extends the global
stellarator confinement database ISCDB. ISHPDB is jointly hosted by IPP and NIFS [1]. The effort is structured byphysics topics led by the acknowledged experts in their respective fields. A first inter-machine study of 1-d data aspart of ISHPDB was given in [2] proving the concept of ISHPDB to result in significant progress. More extended
inter-machine studies on high-β physics, impurity transport, edge physics, aspects of neoclassical transport andconfiguration dependencies will be given at this conference. This contribution focuses on a survey of the ISHPDB
topical structure. The resulting requirements for physics oriented documentation will be summarized. A physics
motivated quality assurance of the database will be discussed. A proposal for the implementation of an ISHPDB
database schema compliant with existing tokamak databases and its interfaces will be introduced.
Keywords: International Stellarator/Heliotron Profile Database, Confinement, Transport

1. From 0d to 1d: transport assessment in 3-d
devices towards reactor capabilities.
A concise documentation of stellarator/heliotron
device operation is necessary for system assessment
aiming at viable stellarator/heliotron reactor concepts.
Consequently, joint databases for global confinement timeτE in 3d devices were initiated as a joint effort of thestellarator/heliotron community. The International
Stellarator/Heliotron Confinement Database (ISHPDB) is
intended to continue this activity and to serve as a common
documentation for physics investigations in 3d magnetic
confinement fusion devices.
The first joint energy confinement scaling study for
3d devices led to the ISS95 scaling [3] which was largely
confirmed with a broader and more extended data-set incorresponding author’s e-mail: dinklage@ipp.mpg.de

the ISS04 study [4]. A particular result of the latter study
was the identification of the impact of the magnetic
configuration.
In view of possible reactor assessments, the studiesof the global (0d) scaling for τE showed a couple of open
issues. In particular, the validity of scaling laws withrespect to extrapolation was discussed by means ofphysical model assessments. Applied on global data, modelcomparison techniques indicated differences in the basic
transport mechanisms between low and high-β data [5]. A
detailed assessment of the impact of plasma β on transport,
however, was hindered by a lack of local transport analyses
and needs to be pursued. High confinement regimes wereassessed in places [6], but a systematic investigation of thedifferences in transport in the different options for device
operation was only recently started for the core electron
confinement [7]. In this conference, this philosophy isProceedings of ITC/ISHW2007 P1-037
extended to more detailed studies on the impact of therotational transform and the shear [8] on confinement
extending the 0d view by inclusion of profile information.
All recent global confinement studies [4-6] led to theconclusion that more detailed insight is required to perform
a target-oriented assessment of performance measures in
3d devices. Nonetheless, global confinement data represent
a relevant part of a full documentation form a basis for any
comparative study.
This paper is a technical report summarizing thecontent and some infrastructure considerations of ISHPDB.
This report summarizes also aspects from working groupmeetings with the intention to communicate these points tothe community in order to discuss and possibly revise theconcepts developed so far.

confinement documentation; an overlap to the previous
topics is enforced to assure the continuation of theInternational Stellarator Confinement Database.

2. General strategy: physics issues towards astellarator/heliotron fusion reactor

Tab.1 Summary of physics topics in addressed in theInternational
Stellarator/Heliotron
ProfileDatabase ISHPDB.

The status of ISPHDB is premature. For the moment
being, files are collected and have to be stored in acommon, reliable infrastructure allowing general access tothe data. Nonetheless, the general structure is to be
developed driven by the necessity from potential reactor
assessments: issues resulting from this perspective define
the necessities for a reasonable documentation andpragmatic approaches should be directed towards the goalof a common database for reactor assessments.
A common 1d profile database for stellarators andheliotron can be regarded as a documentation standard for
performance studies. However, experience in respective
tokamak databases [8] showed that documentation
standards might vary from device to device, e.g. due todiagnostics availability. Moreover, different supplementary
information is required for different issues, e.g. mode
activity which is relevant to high-β discharges, but is lessdocumented for quiescent H-modes.
Therefore, the requirement analysis for any
documentation activity should start at relevant physics
issues. Table 1 summarizes the high priority topics forinter-machine studies which were identified alongcommunity-open, dedicated workshops [9, 10].
The topic high performance operation is intended to
study H-mode physics and further optimum confinement
regimes in stellarators/heliotrons. Differently, the studies
in high-β physics are much more advanced; a report will
be given at this conference [11]. Similarly, comparativeedge physics and divertor operation studies for LHD and
W7-AS are underway [12]. A survey on the
documentation of impurity transport studies will be given
at this workshop as well [13]. CERC studies even serve
as first input for the specific database [14]. Finally,
confinement studies are intended to continue the global

Physics Topics of ISHPDBHigh Performance Operation
High β physics in 3-d devices
Edge physics and divertor operation
Impurity transport
Core electron root confinement (CERC)
Confinement studies

Although the topic list in Tab. 1 is open for revisions,the issues represent stellarator/heliotron specific subjects
whose documentation requirements may differ from topic
to topic or which might be different to requirements fortokamak databases. A more detailed revision ofrequirements will be provided in the next section and a
resulting proposal for a database structure will be given
below. For the moment being, the actual databasedevelopment is planned to be performed in parallel to thephysics studies.
In a first step, the database is a collection of humanreadable files. As a general guideline, the documentation isthe done by scientific papers along with a delivery of all
supplementary material to ISHPDB.
Along with the consideration of physics requirements,
ISPHDB has to take care for the assurance of quality
measures in the database. The definition of quality
standards is a community exercise which has still to be
done. An agreed procedure must incorporate generalstandards but also specific points with respect to thephysics issue. In a first step, the definition of deliveries
needs to be worked out.

3. Functional and technical requirements
In general, the content of ISHPDB covers typicalfusion data. ISHPDB starts mandatory from the 0d dataset
as used for ISCDB. Furthermore, a link to additional
information describes more background which refers to thedataset like magnetic configuration specifications,descriptive documents explaining specifics of the discharge
under consideration etc.. A more specific guideline on thispoint needs to be worked out.

Proceedings of ITC/ISHW2007 P1-037
Beyond 0d data, time traces of the documented
discharges are part of the discharge documentation. Here,the energy content, applied heating, mean density, loop
voltage, temperature signals (ECE, soft-X), mode activity(Mirnov coils) and Hα emission are valuable signals ingeneral.
Space dependent data for electron density, electron
and ion temperature, the radial electric field form finallythe profile database. Moreover, measurements for Zeff andfurther supplementary data necessary for transport analyses
should be provided.

In addition to the data, the magnetic configurations
used for mapping the data onto a common grid in flux
surface coordinates should be provided. Edge physics data
should be stored in real space coordinates.
All experimental data should be provided with theirerror. The squared standard deviation is used for weighting
the data in fitting procedures. The used fit functions are to
be chosen from a catalogue of standardized parametricfunctions [1] or by non-parametric fits.
Consequently, the database should be capable not only
to store data with error bars but also parameters describing
functional dependencies, e.g. to store also predictive results
or outcome of interpretative transport analyses.
In an advanced version of the database, versioning isan essential feature to allow iterative evaluation steps. Thisis also important for the assessment of model assumptions,e.g. different mappings. Consequently, changes in different
versions should be tracked. Search capabilities with respect
to numerical, cardinal (e.g. 5*1019 m-3 < ne < 2*1020 m-3)
and ordinal criteria (e.g. ECRH vs. NBI heating) should bepossible as well as physics criteria (e.g. high-β discharges).
Technical requirements referring to the deployment of
the database will be specified after exploring the first
specific datasets to be included in a database. At present,
both the National Institute for Fusion Science (Toki, Japan)
and the Max-Planck-Institut für Plasmaphysik (Greifswald,
Germany) offer to host the resources publicly and todevelop web based interfaces to allow the community
access the stored data.

4. A tentative database schema

Fig.1

ISHPDB XML schema .

Fig. 1 shows a tree structure representing a proposal
for the ISHPDB data structure. For the description XML
schema [15] was used. With the XML schema definition,
which was chosen for convenience, all data files can bechecked for consistency automatically. Moreover, there
are a number of computing tools available to generate
automated codes and interfaces to application
programming.
As a general approach, data descriptive data fields
form the header of the entries (e.g. data, source etc.).
Then the three data categories form the data entries(globalData, timeTrace, profile). For profiles, choices
between data on a grid, parametric functions andnon-parametric functions are allowed. The specificentries are due to data presently available and are
adjusted to match with the ITER profile database [16].
The schema works with experimental profile datafrom CERC studies as well as data from predictive
calculations for W7-X.
A first exercise to create working interfaces is theadaptation of the ITER profile database interface
definition employed for TASK analyses on LHD [14].

Proceedings of ITC/ISHW2007 P1-037

5. Summary and Outlook
ISHPDB aims at an extension of thestellarator/heliotron confinement database ISCDB withparticular emphasis on reactor relevant issues. Startingfrom physics studies focused on stellarator specific topics,
a requirement analysis both for data base structures anddata handling procedures has been performed and will be
extended along with practical experience.
A first case study was performed leading to aninter-machine comparison of core electron root
confinement [7]. In this workshop, seven contributions
were submitted as a result from the ISHPDB collaboration
covering inter-machine studies on the impact of rotationaltransform and shear [8], extensions of the existing databasewith respect to high beta operation [11], intermachinestudies of impurity transport [13] and comparisons ofplasma edge physics in divertor operation [12]. Therefore,
it can be concluded that ISHPDB is a living community
exerciseaddressing
relevant
topicsforthestellarator/heliotron community. A series of working
group meetings was implemented and is agreed to becontinued to follow the topics and general issues (see also[14]); since fall 2006 two meetings were held, a
continuation is foreseen. The meetings are open to thecommunity and a permanent revision of topics addressed ispart of the database discussion.
The next specific technical step is the provision of thesubmitted data through a web interface allowing a generalaccess to the data. An important task for the near future is
the general agreement on quality assurance measures, i.e.
the definition which data are to be provided and to define
quality standards for the delivered data. This exercise isreasonably done with the data from this workshop.
For the moment being, responsible officers at the
National Institute for Fusion Science (Toki, Japan) and
Max-Planck-Institut für Plasmaphysik (Greifswald,
Germany) are identified for receiving data and forprocessing data files [17]. These contact persons can be
asked for any further details.
This work contributes to the International Stellarator
Profile DataBase (ISHPDB) under auspices of the IEA
Implementing Agreement for Cooperation in theDevelopment of the Stellarator Concept (1992).

References[1]

http://www.ipp.mpg.de/ISHPDB andhttp://ishpdb.nifs.ac.jp[2] M. Yokoyama et al., Fusion Sci. Technol. 50, 395 (2006).
[3] U. Stroth et al., Nucl. Fusion 36, 1063 (1996).
[4] H. Yamada et al., Nucl. Fusion 45, 1684 (2005).
[5] A. Dinklage et al, Nucl. Fusion 47, 1265 (2007).
[6] A. Dinklage et al, Fusion Sci. Technol. 51, 1 (2007).
[7] M. Yokoyama, Nucl. Fusion 47, 1213 (2007).
[8] E. Ascasibar et al., this conference, paper I-01
[9] http://p-grp.nucleng.kyoto-u.ac.jp/ktscwgm2006/[10] http://www.ipp.mpg.de/ISS/CWGM2007/cwgm.html[11] A. Weller et al., this conference, paper P1-039[12] Y. Feng et al., this conference, paper I-06
[13] K. McCarthy et al., this conference, paper I-18
[14] H. Funaba et al, this conference, paper P-040[15] http://www.w3.org/XML/Schema[16] The ITER 1D Modelling Working Group, Nucl. Fusion 40,
1955 (2000).
[17] Please send data files in copy to funaba@lhd.nifs.ac.jp anddinklage@ipp.mpg.de (subject ISHPDB).