The Hybrid Illinois Device for Research and Applications (HIDRA) is a medium-sized toroidal magnetic fusion device housed in the Nuclear Radiation Laboratory and operated by the Center for Plasma-Material Interactions (CPMI) within the Department of Nuclear, Plasma and Radiological Engineering at the University of Illinois at Urbana–Champaign, United States. HIDRA had its first plasma at the end of April 2016 and started experimental campaigns by December of that year. HIDRA is the former WEGA classical stellarator that was operated at the Max Planck Institute for Plasma Physics in Greifswald Germany from 2001 to 2013.
A unique aspect of HIDRA is that it can operate as a stellarator and as a tokamak, hence the hybrid designation. In fact, it should be possible to operate the two modes simultaneously. It operates up to 15 minutes of continuous plasma, with up to 60 minutes in the future and will concentrate on understanding the complex relationship between the plasma and materials inside the vacuum vessel of a fusion device and specifically will concentrate in understanding the complex behavior that flowing liquid metal walls, and in particular liquid lithium, have as plasma-facing materials in such devices. This makes HIDRA one of only a very few fusion devices willing to run liquid lithium as a plasma-facing material (PFM). Others include NSTX, LTX, EAST, T-11M, RFX, FTU and TJ-II.
History Some argue that HIDRA is the "most well traveled fusion device in the world". From its beginnings in France, it has operated in 4 cities in 3 countries. The research goals of the device have dramatically changed over the years, from doing wave heating studies to being a testbed for one of the world's most sophisticated fusion devices, and now to studying the way plasmas interact with the inside wall and materials of fusion devices. In fact, it will be the first toroidal fusion-relevant device that will be solely dedicated to the study of plasma wall (PWI), plasma surface (PSI) and plasma material interactions (PMI).
Centre d’Etudes Nucléaires (1972–1982) HIDRA, started off as a different machine at the Centre d’Etudes Nucléaires in Grenoble, France in 1972. Back then it was called WEGA with construction of the device from 1972 to 1975. WEGA was a joint project between CEA Grenoble and the Max Planck Institute for Plasma Physics in Germany to study RF heating and lower hybrid heating. There were three vacuum vessel that were built, two tokamak and a single stellarator. WEGA primarily operated as a tokamak from 1975 to 1987C. Gormezano et al., Lower Hybrid Heating in the WEGA Tokamak, Symposium on Heating in Toroidal Plasma III, Grenoble, France, 22–26 March 1982, 15042735 despite plans to install the stellarator vessel in 1976 (repairs were needed on the helical coil insulation). Electron and ion temperatures achieved were, Te = 600 – 900 eV and, Ti = 150 – 250 eV. Densities of ne = 1.6×1019 m−3 with a plasma current of IP = 45 – 60 kA and heating power, Pohm = 100 – 130 kW and, PRF = 100 kW. Typical pulse duration was, Δt = 5 – 15 ms and an energy confinement time, τE = 3 – 5 ms.P. Blanc et al., Lower Hybrid Experiments in the WEGA Tokamak, International Meeting on Theoretical and Experimental Aspects of Heating of Toroidal Plasmas, Grenoble France, 28 June 1976, 8311643
WEGA was then converted over to a "classical Stellarator" design with the toroidal coils kept in place and a new vacuum vessel with four helical coils winding around the vessel.R. Frisch et al., Technological Aspects of the WEGA Stellarator Symposium on Fusion Technology, Garnich-Partenkirchen, F. R. Germany, 14–18 June 1976, FR7602990T. Consoli et al., The WEGA Stellarator, Bulletin of Information, Science and Technology 202 (1975) 93-100 It was operated as a Stellarator until 1982 when it moved to the University of Stuttgart, in the then West Germany.
Institut für Plasmaforschung (1982–2000)
In 1982 WEGA moved from Grenoble to the University of Stuttgart in Germany. Unfortunately in Stuttgart it seems that WEGA was not used much. There is not a lot of information from this time and it is very difficult to see what results came out of this 18-year time period. The issues seem to be a lack of enough heating power and cooling. However, IPF did have the stellarator vacuum vessel installed and some of the first magnetic flux surface measurements were performed.H. Hailer et al., 14th European Conference on Controlled Fusion and Plasma Physics, Madrid 1987, 11(1) 423
Max-Planck-Institut für Plasmaphysik (2001–2013) From 2000 to 2001 WEGA moved from Stuttgart to Greifswald. At this stage a new institute had been built in the former East German city to stimulate economic, scientific and educational growth in the region. MPIPP Greifswald was designated to house the brand new modular stellarator W7-X. While W7-X was being built WEGA was brought in to be the machine where much of the diagnostic, heating and control work for W7-X would be tested and perfected.M.Lewerentz et al., First Experiences with the new W7-X Like Control System at the WEGA Stellarator, Fusion Engineering Design 84(7-11) (2009) 1179-1183J. Schacht et al., Stellarator WEGA as a Test-bed for the Wendelstein 7-X Control System Concept, Fusion Engineering Design 83(2-3) (2008) 228-235H. Laqua et al., Test of the Steady State W7-X Control and Data Acquisition System at the WEGA Stellarator Fusion Engineering Design 85(3-4) (2010), 520-524 It also provided a valuable tool in the training and teaching of future generations of fusion and plasma scientists and engineers. In fact, though the name was the same the acronym for WEGA changed to "Wendelstein Experiment in Greifswald für Ausbildung" the Wendelstein experiment in Greifswald for Training.M. Otte et al., The WEGA Stellarator: Results and Prospects, AIP Conference Proceedings 993 (2008), 3
WEGA's magnetic coil systems were run via transformer and rectifier sets that allowed steady state operations. This made WEGA unique among the smaller toroidal fusion devices that normally are pulsed, and only the larger devices such as LHD and W7-X have that kind of steady state capability. Some of the achievements on WEGA include the development of an OXB heating scheme that allows ECRH heating above the cut off density for the electrons in the plasma.Y. Podoba, Radio Frequency Heating on the WEGA Stellarator IPP report, IPP 13/12, October 2008Y. Y. Podoba et al., Direct Observation of Electron-Bernstein Wave Heating by O-X-B Mode Conversion at Low Magnetic Fields in the WEGA Stellarator, Physical Review Letters, 98 (2007) 255003 This allowed densities almost 100 times higher to be achieved, where temperatures were on average around Te = 15 eV and densities around ne ~ 1018 m−3.K. Horvath et al., Langmuir Probe Measurements in the WEGA Stellarator, Contributions to Plasma Physics 44(7-8) (2004), 650-655K. Horvath et al., Investigations of the Electron Temperature Profiles at the WEGA Stellarator, Plasma Physics and Controlled Fusion 48 (2006) 315M. Otte et al., Overdense Plasma Operation in the WEGA Stellarator, Contributions to Plasma Physics 50(8) (2010) 785-789 Ion temperatures around Ti = 1-2 eV.J. Chung et al., Time Resolved Coherence-Imaging Spectrometer on WEGA Stellarator Plasma Physics Controlled Fusion, 47 (2005) 919 The W7-X control system was tested on WEGA showing the real time capability of measuring plasma parameters and control of the machine. It was demonstrated, that despite being a stellarator, a plasma current could be driven via microwave heating of the plasma.H. P. Laqua et al., Fundamental Investigation of Electron Bernstein Wave Heating and Current Drive at the WEGA Stellarator, IAEA, EX P-6 18E. Chlechowitz, Plasma Current and Pressure Measurements at the WEGA Stellarator, PhD, Greifswald, April 2010
Furthermore, a heavy ion beam probe (HIBP) was also developed for the measurement of radial profiles of the electric plasma potential.L. I. Krupnik et al., The Heavy Ion Beam Probing Development for WEGA Stellarator, Fusion Science and Technology 50(2) (2006), 276-280Y. Podoba et al., First HIBP Results on the WEGA Stellarator, AIP Conference Proceedings 993 (2008) 235 In 2013 the last experiments were performed and WEGA was slowly decommissioned as operations for W7-X started to ramp up.M. Otte et al., Overview of Recent Results on the WEGA Stellarator Nukleonika 57(2) (2012), 171-175 WEGA was either going to be scrapped or if a suitable research group was found would be donated. In the Fall of 2013 a suitable donor was found, the University of Illinois at Urbana-Champaign, and details for the transfer were completed in the summer of 2014.
Center for Plasma Material-Interactions (2014–present)
With W7-X operations starting in 2014, the space occupied by WEGA and its power systems was taking up much needed real-estate for the Thomson Scattering system and a cryogenic pellet injection system. During the 2013 SOFE conference, Daniel Andruczyk, a former Post-Doc on WEGA, met with some former colleagues and it was suggested that the University of Illinois could potentially take WEGA to the USA. After a year of negotiating between the director of the Center for Plasma Material Interactions, David Ruzic, the university and IPP, the funds were secured to make it happen. Andruczyk was brought on to lead the project of dismantling and shipping WEGA to the Urbana-Champaign Campus in Illinois. Upon arrival the Machine was renamed the Hybrid Illinois Device for Research and Applications. The Hybrid part being that it still has the tokamak capabilities, not only the stellarator ones.
It took nearly 8 weeks over the autumn of 2014 of dismantling the device in Germany and was packed and shipped to the US in October. By early 4 November shipping containers worth of fusion device arrived by flat bed-truck to the University of Illinois at the Center for Plasma Material Interactions. Aside from lab personnel, the universities facilities and services division were heavily involved in helping to off load, move in and assemble much of the larger, heavier components. Construction began in earnest with the transformers and rectifiers for the helical and toroidal magnetic coils moving in first. Once these were established then the base was brought in and the yokes, center-stack, half-tori and vertical field coils all installed over the next ten days.D. Andruczyk et al., HIDRA: Hybrid Illinois Device for Research and Applications, Fusion Science and Technology 68 (2015) 497
HIDRA foremost is an educational tool for training future fusion scientists and engineers. Everything with the machine is done such that students can use it. The control system was written by senior undergrad and grad students and allows the machine to be controlled from one computer via a LabView program. This also sends out the trigger signals that are needed to fire the various data acquisition and diagnostic systems. HIDRA essentially can be controlled and run by a single person.D. Johnson et al., HIDRA control system (HCS): A LabVIEW-based program to control the Hybrid Illinois Device for Research and Applications, Fusion Engineering and Design 128 (2018) 215-222
Applications
First Plasma (2016)