MDSplus integration at TCABR tokamak: Current status
Introduction
Scientific experiments in different countries, nowadays, are heavily focused on collaborations with exchange of scientists, data remote access and even remote control of the experiments [1]. It is customary that each plasma physics laboratory has a proprietary scheme of the control and data acquisition system. It means that each laboratory has its own way of controlling the experiment and retrieving data from the database. As fusion research relies, to great extent, on international cooperation, these private systems make it difficult to follow the work for visiting and overseas researchers. Thus, standardized computational tools are becoming extremely important.
In this context, the MDSplus (Model Driven System Plus) framework has been developed by several researchers across the globe for data acquisition and storage [2]. It is an open source software tool that allows all experimental or calculated data to be stored into a single, self-descriptive, hierarchical structure.
The TCABR (Tokamak Chauffage Alfvén Brésilien, R = 0.615 m, a = 0.18 m, Bt = 1.1 T, Ip ≤ 100 kA, n0 ≤ 4 ×1019 m−3) is a small tokamak installed at the Plasma Physics Laboratory in the Institute of Physics of the University of São Paulo, Brazil [3]. This device has contributed with relevant works to the community of plasma physics and nuclear fusion, and the remote participation plays an important role there. In the TCABR, the control and data acquisition system have been updated to be inserted into an internationalized research program [4]. This has been done by employing the MDSplus, which is widely adopted in the fusion community. After three years of use, the system installed on TCABR has proved extremely efficient and significantly increased the productivity of the scientists involved in the experiments, regardless of whether they are locally at the TCABR or accessing the system remotely from their home laboratories.
The formerly TCABR CODAS system worked in a serialized way: once all signals were available, a main program formatted each one of them properly and sent them to the database. Currently, all diagnostics, or set of diagnostics, operate independently, even the legacy drivers (i.e., low bandwidth VME instrumentation). Each one receives its settings and complementary information from the main controller (or from another computer in the internal network) by messages over TCP/IP and, after the physical trigger, each diagnostics acquires and populates its own MDSplus tree with the signals, setup information, calibration, etc., and then they send the trees to the main database server.
Furthermore (subject of this article), with MDSplus, the web data can be viewed in any modern browser which support HTML5, just using JavaScript API. This approach is a fast way for programming and it is easier to maintain compared to dynamic content pages (with PHP or Python). It is particularly useful in the logbook webpage, where just a few signals are relevant.
The progress with the use and implementation of MDSplus in TCABR is described in this article. In the next section, we briefly describe the old control, data acquisition and analysis, and remote access system up to the first implementation phase of MDSplus. The current phase of the update TCABR CODAS is described in Section 3 (general description of the upgraded system) and Section 4, where we present the visualization system developed. Finally, we present what it is going to be done in the coming years (Section 5).
Section snippets
TCABR legacy CODAS
By 2010, the TCABR control system and data acquisition was based on the VME instrumentation standard with Motorola 68040 and Motorola 68060 CPU and OS9 operating system, an ATCA (Advanced Telecom Computing Architecture) crate with Intel Core 2 Duo CPU and Linux operating system, computers with PCI boards and oscilloscopes. ADC modules of 12-bit resolution were available for data acquisition [5]. The VMEs handled most of control and data acquisition, while the ATCA were dedicated for
Current system
In implementing new features and newer data acquisition systems (DAS), one main challenge is to keep backward compatibility, i.e., avoid compromise the legacy drivers still in use in the laboratory. To easier handle this issue, the centralized and serialized CODAS was converted in distributed system. Each diagnostic (or set of diagnostics) manages a local MDSplus server in its controller, where it builds and populates its own tree file. After the end of a plasma discharge and data acquisition,
Data visualization
New ways to visualize the MDSplus data have been also implemented, that are particularly useful for fast characterization of the plasma discharge. MDSplus now brings built in a Web Server Gateway Interface (WSGI) that allows querying information from the plasma discharge and signals recorded in the MDSplus trees with simple JavaScript on an HTML page [11]. More specifically, web pages using Asynchronous JavaScript and XML (AJAX) technology can use XMLHttpRequest API access data or events of
Future enhancements
The use of MDSplus in the TCABR is now quite consolidated for storage and retrieval of tokamak discharge data, by using local file trees for each diagnostic, and then synchronized them with the main MDSplus database, or by an intermediate process, if the MDSplus is not available for the DAC operational system, as previously explained.
By now, the main concern is to define and apply a comprehensive and unified protocol to configure and control each diagnostic via HTTP. Although the current
Summary
Remote participation and remote access to experimental data is the main factor in the collaborative work between scientists in different laboratories around the world. The implementation of MDSplus tools system has become a standard in plasma physics and nuclear fusion. Hence reducing significantly development tools for Control, Data Acquisition and Data Analysis and Remote Access.
Here we presented the current integration of MDSplus in TCABR, where we developed a modular approach for several
Acknowledgements
This work has been supported by The National Council for Scientific and Technological Development (CNPq), and by grant 11/50773-0 of São Paulo Research Foundation (FAPESP).
References (12)
- et al.
Remote operation of the vertical plasma stabilization @ the GOLEM tokamak for the plasma physics education
Fusion Eng. Des.
(2015) - et al.
Future directions of MDSplus
Proceedings of the 9th IAEA Technical Meeting on Control, Data Acquisition, and Remote Participation for Fusion Research
Fusion Eng. Des.
(2014) Tokamak TCABR: Acquisition system, data analysis, and remote participation using {MDSplus}
Proceedings of the 8th {IAEA} Technical Meeting on Control, Data Acquisition, and Remote Participation for Fusion Research
Fusion Eng. Des.
(2012)- et al.
TCABR data acquisition system
Fusion Eng. Des.
(2000) Commonalities and differences between MDSplus and HDF5 data systems
Fusion Eng. Des.
(2010)- et al.
MDSplus evolution continues
Fusion Eng. Des.
(2012)