Magnum-PSI

Magnum-PSI: scientific and technical challenges

As part of the TEC collaboration and within the framework of Euratom, the FOM Institute Rijnhuizen is building a new machine to study plasma wall interactions. This apparatus, Magnum-PSI, will be world-wide unique and provide an important new experimental facility in the range of experiments that are available to PSI research for ITER and reactors beyond ITER. The uniqueness of Magnum-PSI lies first in its ability to access simultaneously the several aspects of PSI in the combination of which ITER essentially differs from present day experiments:

 

1. Large ion fluency and continuous operation, which leads to ‘macroscopic’ modification of plasma-facing surfaces.
2. High power density (5-10 MW m-2) with low plasma temperature (< 5 eV) such that materials are close to, or at the energy threshold for sputtering, but have high surface temperature and are therefore near their materials limits for stress/strain, etc.
3. Strong plasma-surface coupling: the high plasma density leads to short mean free paths for dissociation/ionization of eroded atoms or molecules in comparison with the linear dimensions of the plasma.
4. Access to plasma diagnostics and in-situ surface analysis.

 

The steady-state high flux of up to 1024 ions m-2s-1 at a plasma temperature in the eV range, magnetic field of 3 T, and large beam diameter make Magnum-PSI a unique experiment, bringing the relevant parameters typically an order of magnitude beyond what is presently available in linear plasma devices, and into the realm of the ITER divertor. It will be the only device so far to enter the strongly coupled regime, in which molecules and dust particles that come off the surface are trapped and remain part of the plasma-surface interaction system, and thus will allow relevant studies of dust formation, re-deposition, migration and hydrogen retention. The steady-state and high flux capability, combined with the large flexibility and easy access, allow post mortem analysis which in present devices normally occurs only every 1-2 years.

Design activities in the Magnum-PSI project

The major part of the definition and design phase of the Magnum-PSI project has now been completed. In what follows, we summarize some of the important activities that occurred up till now.
We have made the complete design of the Magnum-PSI device. The results can be observed in figure 1. Shown are (from left to right) the source-, heating- and target chamber with pump ducts. The vacuum system is constructed in modules which are movable and placed on a rail system. Next to these, the pumping station for the third stage is shown. The vacuum system is surrounded by the movable superconducting magnet which is placed on a rail. On the right hand side, the target station with target and target manipulator are visible. In the target analysis station, the targets can be analyzed in detail with surface analysis equipment.

 

 

Figure 1.  Total overview of the Magnum-PSI experiment with target station and target manipulator. Shown are (from right to left) the source-, heating- and target chamber with pump ducts. Next to these, the pumping station for the third stage is shown. On the right hand side, the target station with target and target manipulator are visible. In the target analysis station, the targets can be analyzed in detail with surface analysis equipment.

 

Figure 2.  Detail of the Magnum experiment. Shown are (from left to right) the source-, heating- and target chamber with pump ducts and the superconducting magnet system.

 

In the following sections, we describe some of the highlights in the project.

 

• Vacuum system
• Superconducting magnet system for Magnum-PSI
• Plasma beam and additional heating
• Target Station
• Cooling system
• Control and Data Acquisition
• Outlook
• Movie: The construction of Magnum-PSI

 

Vacuum system

The Magnum-PSI vacuum system has been designed, manufactured and installed. The pumping systems (turbo molecular and roots blower systems) have been commissioned. The testing of the complete system including the control and part of the data acquisition system has been successfully completed.

 

 

Figure 3. The vacuum system of the Magnum-PSI. From left to right: the source-, heating- and target chamber which are placed on a rail system.

 

 

Figure 4. The Magnum-PSI vacuum system with plasma source

 

 

Figure 5. The Magnum-PSI vacuum system with target station

 

 

Figure 6. The roots blower pumps

 

 

Figure 7. The turbo molecular pumps in the basement

 

 

Figure 8. Testing of the vacuum system for Magnum-PSI

 

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Superconducting magnet system for Magnum-PSI

The magnet has a warm bore of 1300 mm and the axial length is 2450 mm. The magnet system has 8 evenly distributed radial access ports of 210 mm diameter each located at two axial positions. These ports allow for good diagnostic access of the experiment. A schematic picture of the superconducting magnet system is given in figure 9.
The superconducting magnet system is now under construction at the manufacturer site. Part of the winding of the magnetic coils has been completed. End 2009, the assembled superconducting magnet system will be installed at Rijnhuizen and tested with the Magnum set-up.

 

 

Figure 9. The 3T superconducting magnet system has been ordered beginning of February 2007

 

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Plasma beam and additional heating

Extensive experiments occurred in the Pilot-PSI experiment on the high flux plasma source and additional heating methods (so-called Ohmic heating and RF heating). The output of the plasma beam (flux density) is within specifications. We will now further concentrate on broadening of the plasma beam diameter to the specified 10 cm.

 

Extensive testing has occurred on RF heating of the plasma beam. Our theoretical understanding has increased significantly and we are now ready for developing and testing different antennae concepts. The work on RF heating is done in close collaboration with KMS/RMS Brussels and the Politecnico di Torino.

 

Figure 10a. Modeling of the RF antenna for Magnum-PSI at the Politecnico di Torino

 

 

Figure 10b. Experimental set-up which is built for proof of principle of RF-heating

 

The Magnum-PSI team has reached the second major milestone in the construction of the plasma wall experiment Magnum-PSI. They completed the construction of the full plasma source system with cooling, gas feed, control and data acquisition, power supplies and safety system. On the 18th of June, the first plasma was made in Magnum-PSI which showed excellent operation of the entire system.

 

 

Figure 11. The high flux plasma source developed in Pilot-PSI (left). Experiments in Pilot-PSI on the plasma source

 

 

Figure 12. The high flux plasma source installed in Magnum-PSI

 

 

Figure 13. The power supplies for the plasma source. The power supplies have been designed and made by the University of Eindhoven.

 

 

Figure 14. The installation of the plasma source in the movable manipulator tube

 

 

Figure 15. The first plasma in the Magnum-PSI experiment, Thursday 18th of June. The plasma is a hot gas of charged Argon-ions and electrons.

 

 

Figure 16. The control room of the Magnum-PSI experiment. The high flux plasma source is tested in Magnum-PSI.

 

 

Figure 17. Magnum-PSI with plasma on

 

 

Figure 18. Experiments on beam broadening: three-channel plasma source

 

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Target Station

In FZ-Jülich, the definition and design activities on the target station and manipulator are finalized. The procurement of the system has started and the building activities are ongoing. The analysis chamber has been installed (see figure 20). The further assembly and testing of the target station will occur in 2009.

 

Figure 19. Design of the target station for Magnum-PSI

 

 

Figure 20. The target station under construction

 

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Cooling system

The construction of the cooling system for Magnum-PSI is finalized (see figure 21). The high pressure cooling circuit for the plasma source and the target and the cooling tower for additional cooling capacity are in the testing phase. The cooling for the vacuum pumps, vacuum vessel and power supplies is completed.

 

 

Figure 21. The cooling system of Magnum-PSI

 

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Control and Data Acquisition

We have defined the control and data acquisition system for the Magnum-PSI experiment. An overall functional design of the control and data acquisition system for Magnum-PSI has been made. The system choices are made and the first parts of the control system has been purchased and tested. We have specified the vacuum, cooling and safety requirements and implemented these in the Magnum-PSI control system.

 

Figure 22. Overview of the architecture lay-out of the CODAC system for Magnum-PSI

 

 

Figure 23. Overview of the hardware lay-out of the CODAC system for Magnum-PSI

 

 

Figure 24. Data base and data viewer

 

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Outlook

Magnum-PSI will be further constructed and tested at FOM-Rijnhuizen in Hall B. An overview of the future hall B with the Magnum-PSI experiment is displayed in figure 25 and figure 26. In 2009, the source, magnet and target station system will be installed and tested. A basic Magnum-PSI device with most of the subsystems will be ready in 2010.

 

Figure 25. The overview of the experiment and location of the cooling area, laser room and control room

 

 

Figure 26. Overview of Magnum-PSI in 2010

 

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Movie

The construction of Magnum-PSI (WMV - 2MB)