Wendelstein 7-X
Topical Research
Project Status (31th
December 2008)
The experiment Wendelstein 7-X is being constructed out of five modules which are nearly identical in construction. The modules are being preassembled and will finally be assembled in a circle in the experimental hall.
Machine
Magnet system
The superconductor for the non-planar and planar coils, consisting of 243 copper niobium titanium wires in an aluminium jacket was produced by the European Advanced Superconductors/Outokumpo consortium (formerly Vacuumschmelze/Europa Metalli Superconductors). Production of the superconductor has been finished.
Manufacture Manufacture of the 50 non-planar superconducting magnetic coils, which will later generate the magnetic field cage for the plasma, has been taken on by the German-Italian consortium Babcock Noell Nuclear GmbH/Ansaldo. Coil production was finished in March 2008 after delivery of the 50th coil.By the end of December 39 successfully tested coils were delivered to the IPP in Greifswald, two coils are being tested or prepared for tests at CEA/Saclay, four coils are stored at CEA, and five coils are kept in store at BNG in Zeitz.
Twenty planar magnet coils are being produced by the British company Tesla. The company has completed production; 19 coils have been tested successfully until now. One faulty coil has been repaired by the manufacturer and will be re-tested in 2009.
The superconducting bus system of the coil connections joints the coils together and to the power supply. Design, manufacture and assembly of the bus system are within the responsibility of the Jülich research center (FZJ). Manufacturing by FZJ as well as the preparatory design and the collision tests of the components by IPP are being continued according to plan.The assembly of the brackets and supports of the busbar system at the second module have started. The preparation of the busbars of the first magnet module has been completed. IPP is designing the supports of the bus system for the module separation planes. The fitting of the joints between the busbars and the coil connections is continuing to be trained within a special qualification programme. Manufacturing of the joints by FZJ and manufacturing of the components for the joint isolation are continued according to schedule.
Support and vault structure
The support and vault structure for the magnets is produced by the Spanish company ENSA. Production of the support structure is proceeding according to schedule. Three modules were delivered by ENSA; two modules have been prepared for assembly and are meanwhile connected to the coils. The third module is being prepared for the assembly. Manufacturing of the fourth module is nearly completed and machining of the last module has started with Rovera. Supply of GRP-bushings by IMA Dresden and sliding bearings by SKF has been completed. Final assembly by Zanon (Italy) for the pre-series and the first module have been finished, the assembly for the remaining four modules has started.
Coils are supported one with the other by narrow, lateral, planar and contact elements. All pads and frames of the narrow support elements for the first two modules – except for those at the module separation plane – have been assembled and those for the third module have been prefabricated. After the measurement and final machining the supports have been assembled in the fifth half module. The unmachined parts of the lateral support elements have been delivered for all modules (except for the module separation plane), those of the first two modules have been welded. All planar support elements of the first two modules have been delivered and assembled. The planar support elements of the third module are being prefabricated. The contact support elements of the first module have been delivered and assembled and those of the second module have been manufactured.
Fastening elements for the first two modules such as bolts, screws and sleeves, cotters and plates which connect the coils and cryo legs to the central ring have been mounted at the first two modules. The elements for the third module have been delivered and the manufacturing of the elements for the fourth module is being prepared. The manufacturing drawings for the fastening elements at the module separation planes are being prepared.
Power supply for the coils
ABB (CH) is manufacturing the high current supply and the protection system of the coils. Power supply has been fully accomplished and tests are on schedule.
The quench detection system is to protect the magnets from break-down of the superconductivity – the so called quench. The prototype is being developed together with the Karlsruhe Research Centre (FZK). Quenches were induced during the cold tests of the planar and non-planar coils with CEA/Saclay in order to test the system. The detection units have detected all quenches rapidly and reliably. Thus the development of the system has been completed successfully and serial production is starting.
Coil tests
Acceptance inspections of all coils take place at the Low Temperature Institute at the research centre of the CEA in Saclay in France. Following production, each coil is transported to Saclay where it is cooled to a low temperature in a cryostat and operated with nominal current. The design reserve is then checked in relation to the quench – the collapse of the superconducting properties. The first non-planar coil arrived in Saclay 19 June 2003. The coil tests at CEA/Saclay proceed without faults and according to plan at present. During the last three months two planar and five non-planar coils were tested.
A second test stand, called TOSKA, in the Karlsruhe Research Centre, which was intended to expand test capacity, is being prepared for operation. But due to delays in completion, the plan had to be given up the more as FZK urgently required resources to supervise completion of current supplies. It was therefore decided that the Karlsruhe coils had to be sent to CEA in Saclay. Nevertheless, TOSKA shall be completed as an option in case of serious failure of the CEA test stand.
Cryostat
The cryostat is the heat insulating vessel for the low-temperature magnet coils. The ring shaped insulating chamber with an internal diameter of approximately 12 metres and external diameter of approximately 16 meters consists of the inside-located plasma vessel, the outer vessel and 299 ports which allow access to the plasma vessel for heating, cooling, pumps and measuring devices. The cryostat also contains the thermal insulation, connectors, mechanic support elements and instruments. The entire superconducting coil system is housed in the evacuated chamber.
MAN DWE, the manufacturer of the plasma vessel, has meanwhile completed production of all plasma vessel segments. All vessel components have been delivered and the first two modules have been assembled. Installation works are proceeding according to schedule. The assembly of the fifth and sixth half module started in September. MAN DWE have manufactured and supplied all vertical supports. The first three vertically arranged plasma vessel supports have been welded onto the lower shell of the outer vessel and measured.
The outer vessel is being manufactured by MAN DWE, too. Production and delivery continued according to plan. The half-shells of the first modules have been delivered. The test assembly and the following final test at the last module are scheduled for March 2009.
The vacuum-tight vessel ports which lead outwards from the plasma vessel through the cryostat are being manufactured by the Swiss company Romabau. Production had been finalized. With the delivery of 254 ports to the IPP Gerinox performed their delivery contract. Measuring of ports prior to installation is on schedule.
The low-temperature insulation for the plasma vessel is produced by the Deggendorfer Werft MAN DWE. Segments of the thermal insulation for the third module have been mounted onto the plasma vessel. Insulation of the outer vessel has been carried out since September. The design for the thermal insulation of the outer vessel is proceeding. Due to the cramped available space inside the cryostat, the detail design engineering for the thermal insulation and collision control with the neighbouring components has become very time consuming.
Manufacturing of current leads is at the responsibility of the Karlsruhe Research Centre. FZK prepared the production drawings for the prototype of the current lead; thereafter the IPP revised and approved them for fabrication. The final design will be released for serial production after testing of prototypes. FZK procured the high-temperature superconductors needed for the testing of the prototypes. 27 aluminium-steel adapter pieces were manufactured; seven out of them have not been accepted due to geometrical deviations.
The Helium-cryo pipelines inside the insulation-vacuum area of the cryostat supply the coils, the support structure, and the thermal insulation with helium. They are being produced by Romabau (Switzerland). Design and production has been broken down into eight batches. The design of the cryo-piplines for the first module by IPP and the preparation of the production drawings by the company ibk have been nearly finished. Coarse models for the first half of the second module (lot 1 to 4) have been produced. Pipes of the 1st to 4th lot of the first module have been manufactured and delivered. The fixtures for the whole module have almost been manufactured. The design of the pipes and fixtures and the fabrication of all components are still creating bottlenecks. So far the enormous delays in delivery of the pipes and fixtures could still have been compensated by reorganising the assembly process. To avoid further delays design and manufacturing have to speed up.
The company Linde Kryotechnik is proceeding with the completion of the Helium-cooling plant. It has been set up in Greifswald and commissioning tests have been conducted since. Activities for the test programme of the cooling plant control system are proceeding. The test cryostat which is needed for the acceptance of the cooling plant is being manufactured. It will be equipped with a heater to simulate the thermal load occurring during future experiments.
The tendering process for the manufacturing of the power supply for the glow discharge electrodes, which are designed for the cleaning of the plasma vessel, has been finished successfully. The order was placed with Puls Plasmatechnik Dortmund (PPT).
In-vessel components
The Wendelstein 7-X is being equipped with a divertor for energy and particle removal. The heavily loaded baffle plates of the divertor are manufactured from CuCrZr and CFC, which is a material combination that has been proposed for ITER and qualified by prototypes. Only as a start and in order to save time, the components shall firstly be mounted as complete as possible, but then (except for only a few components) operated without cooling (Scenario 3). Instead of the cryo-pumps and the actively cooled divertor an inertially cooled divertor (test divertor unit, TDU) will be installed at first.
The functional specification for the components has been drawn up. The detailed design of the individual modules and their support frames is being continued. One test module has been manufactured and will be tested in the test device GLADIS in Garching. Four different kinds of graphite will be tested to specify the best material. The design of the support frames and adjusting devices has been finished. Activities for the completion of the heat shields and baffle modules are on schedule. Meanwhile MAN DWE has provided 250 wall panels and the process is on schedule. The activities for the cooling water pipeline system for the wall protection are being continued. A manufacturing contract for the manifolds has been concluded. The flexible tubes for the first lot have been delivered and the call for tender for the second lot has been started. Measures for speeding up the process were worked out to avoid risks for deadlines as to assembly of the cooling water pipes, heat shields and baffles in the workshops of Garching.
Heating systems
Microwave heating
Within the framework of a collaboration agreement between IPP and Karlsruhe Research Centre (FZK) concluded in April 1998, the FZK has assumed full responsibility for supplying the microwave heating system for the Wendelstein 7-X. The "Microwave Heating Project" set up for this purpose is coordinating the different contributions from other laboratories and industry. Ten microwave emitters – so-called gyrotons – with a total microwave heating capacity of 10 megawatts at a frequency of 140 GHz in continuous operation are to be made available for plasma production and plasma heating – the worldwide biggest microwave heating system under construction.
The three prototypes have been prepared since then; two of them were designed in Europe together with the French company Thales Electron Devices (TED) and one in the USA at the Communication Power Industries Inc. (CPI). Seven more Gyrotrons were ordered with Thales Electron Devices after invitation to tender.
In contrast to the quality which was proofed during the period of the gyrotron development and for the first serial tube, later produced TED-serial gyrotrons have shown insufficient test results: TED has stopped the experiments at the serial gyrotron SN5. The gyrotron cannot be operated reliably neither with short nor long pulses and was dismounted. Tube manufacturing with TED is interrupted for six months to start a R&D programme with FZK.
Microwave transmission line
The Institute for Plasma Research (IPF) at the University of Stuttgart projects and controls the transmission line which serves for the quasi-optical transmission of microwaves. Their deflection is enabled by special reflectors.
Manufacturing of the new receiver for the grid coupler enabling the simultaneous measuring of the overall performance with a bolometer as well as the mode-selective signal via an optimized horn with successive microwave detector has been completed. The design of the shielding casings between the spires on top of the microwave towers and the torus windows has been continued. The concept for the integration of a directional coupler at the reflectors M 14 has been developed and the stray radiation absorbers in the spires have been designed. Manufacturing of the absorbers in the area of the torus windows have been advanced.
Radio-frequency and neutral-particle heating
Work on the radio-frequency and neutral-particle heating is currently being performed with fewer resources. Nevertheless, the first section of the neutral particle heating, which is designed to produce 10 Megawatt heating output when commissioned, is now under construction.
Assembly
Assembly of the first two half modules on the assembly stands Ia and Ib was duly finalised in March 2008. The second pair of mirror-symmetrical magnet half modules was completed on the meanwhile free assembly stands. Assembly works for the third magnet module which started in September have been continued. The second module is mechanically complete; the activities at the busbar system have started. At the first magnet module the helium piping, the bus system and the instrumentation are being completed. Preparation of the outer vessel shells for the first module has started. The assembly of massive reinforcement fixtures and plasma vessel supports which were mounted for the first time was successful. Considerable efforts are currently being made to facilitate the trouble-free installation of the bus- and helium pipeline system which is more time-consuming than expected. Therefore the assembly of the bus and helium pipeline systems have been parallelised. The delayed delivery of the helium pipeline components shall be compensated by reorganisation of the assembly. The activities for the low-voltage-high-current supply unit and the cooling water supply are being continued according to schedule.
Diagnostics
During the setting-up of the measuring instruments, which will later record the status of the plasma, attention was paid to the diagnostics which will be required to commission the WENDELSTEIN-7X for either supervisory tasks or interpretation of the initial experiments. These include diagnostics for the plasma boundary and divertor, microwave diagnostics, charge exchange neutral diagnostics, spectroscopy for the diagnosis of impurities, Thomson scattering, X-ray tomography, magnetic diagnostics and neutron diagnostics.
Works for the completion of numerous diagnostics are on schedule, however, the increasing shortage of designers is becoming more and more problematic.
Project progress
In the testing device at CEA only twelve coils will have to be tested; the completion of the tests is expected for the middle of 2009. Provision of main components of the cryostat is going according to schedule. Design and manufacturing of the helium cryo-pipes are still critical. Additional resources in terms of personnel for design tasks and collision analyses are provided by IPP. The situation for providing the busbars with suitable supports, fixtures and special clamps by FZJ has stabilised and the deliveries are on schedule. Development and production of components inside the plasma vessel is being executed according to schedule.
The experiment Wendelstein 7-X is being constructed out of five modules which are nearly identical in construction. The modules are being preassembled and will finally be assembled in a circle in the experimental hall.
Machine
Magnet system
The superconductor for the non-planar and planar coils, consisting of 243 copper niobium titanium wires in an aluminium jacket was produced by the European Advanced Superconductors/Outokumpo consortium (formerly Vacuumschmelze/Europa Metalli Superconductors). Production of the superconductor has been finished.
Manufacture Manufacture of the 50 non-planar superconducting magnetic coils, which will later generate the magnetic field cage for the plasma, has been taken on by the German-Italian consortium Babcock Noell Nuclear GmbH/Ansaldo. Coil production was finished in March 2008 after delivery of the 50th coil.By the end of December 39 successfully tested coils were delivered to the IPP in Greifswald, two coils are being tested or prepared for tests at CEA/Saclay, four coils are stored at CEA, and five coils are kept in store at BNG in Zeitz.
Twenty planar magnet coils are being produced by the British company Tesla. The company has completed production; 19 coils have been tested successfully until now. One faulty coil has been repaired by the manufacturer and will be re-tested in 2009.
The superconducting bus system of the coil connections joints the coils together and to the power supply. Design, manufacture and assembly of the bus system are within the responsibility of the Jülich research center (FZJ). Manufacturing by FZJ as well as the preparatory design and the collision tests of the components by IPP are being continued according to plan.The assembly of the brackets and supports of the busbar system at the second module have started. The preparation of the busbars of the first magnet module has been completed. IPP is designing the supports of the bus system for the module separation planes. The fitting of the joints between the busbars and the coil connections is continuing to be trained within a special qualification programme. Manufacturing of the joints by FZJ and manufacturing of the components for the joint isolation are continued according to schedule.
Support and vault structure
The support and vault structure for the magnets is produced by the Spanish company ENSA. Production of the support structure is proceeding according to schedule. Three modules were delivered by ENSA; two modules have been prepared for assembly and are meanwhile connected to the coils. The third module is being prepared for the assembly. Manufacturing of the fourth module is nearly completed and machining of the last module has started with Rovera. Supply of GRP-bushings by IMA Dresden and sliding bearings by SKF has been completed. Final assembly by Zanon (Italy) for the pre-series and the first module have been finished, the assembly for the remaining four modules has started.
Coils are supported one with the other by narrow, lateral, planar and contact elements. All pads and frames of the narrow support elements for the first two modules – except for those at the module separation plane – have been assembled and those for the third module have been prefabricated. After the measurement and final machining the supports have been assembled in the fifth half module. The unmachined parts of the lateral support elements have been delivered for all modules (except for the module separation plane), those of the first two modules have been welded. All planar support elements of the first two modules have been delivered and assembled. The planar support elements of the third module are being prefabricated. The contact support elements of the first module have been delivered and assembled and those of the second module have been manufactured.
Fastening elements for the first two modules such as bolts, screws and sleeves, cotters and plates which connect the coils and cryo legs to the central ring have been mounted at the first two modules. The elements for the third module have been delivered and the manufacturing of the elements for the fourth module is being prepared. The manufacturing drawings for the fastening elements at the module separation planes are being prepared.
Power supply for the coils
ABB (CH) is manufacturing the high current supply and the protection system of the coils. Power supply has been fully accomplished and tests are on schedule.
The quench detection system is to protect the magnets from break-down of the superconductivity – the so called quench. The prototype is being developed together with the Karlsruhe Research Centre (FZK). Quenches were induced during the cold tests of the planar and non-planar coils with CEA/Saclay in order to test the system. The detection units have detected all quenches rapidly and reliably. Thus the development of the system has been completed successfully and serial production is starting.
Coil tests
Acceptance inspections of all coils take place at the Low Temperature Institute at the research centre of the CEA in Saclay in France. Following production, each coil is transported to Saclay where it is cooled to a low temperature in a cryostat and operated with nominal current. The design reserve is then checked in relation to the quench – the collapse of the superconducting properties. The first non-planar coil arrived in Saclay 19 June 2003. The coil tests at CEA/Saclay proceed without faults and according to plan at present. During the last three months two planar and five non-planar coils were tested.
A second test stand, called TOSKA, in the Karlsruhe Research Centre, which was intended to expand test capacity, is being prepared for operation. But due to delays in completion, the plan had to be given up the more as FZK urgently required resources to supervise completion of current supplies. It was therefore decided that the Karlsruhe coils had to be sent to CEA in Saclay. Nevertheless, TOSKA shall be completed as an option in case of serious failure of the CEA test stand.
Cryostat
The cryostat is the heat insulating vessel for the low-temperature magnet coils. The ring shaped insulating chamber with an internal diameter of approximately 12 metres and external diameter of approximately 16 meters consists of the inside-located plasma vessel, the outer vessel and 299 ports which allow access to the plasma vessel for heating, cooling, pumps and measuring devices. The cryostat also contains the thermal insulation, connectors, mechanic support elements and instruments. The entire superconducting coil system is housed in the evacuated chamber.
MAN DWE, the manufacturer of the plasma vessel, has meanwhile completed production of all plasma vessel segments. All vessel components have been delivered and the first two modules have been assembled. Installation works are proceeding according to schedule. The assembly of the fifth and sixth half module started in September. MAN DWE have manufactured and supplied all vertical supports. The first three vertically arranged plasma vessel supports have been welded onto the lower shell of the outer vessel and measured.
The outer vessel is being manufactured by MAN DWE, too. Production and delivery continued according to plan. The half-shells of the first modules have been delivered. The test assembly and the following final test at the last module are scheduled for March 2009.
The vacuum-tight vessel ports which lead outwards from the plasma vessel through the cryostat are being manufactured by the Swiss company Romabau. Production had been finalized. With the delivery of 254 ports to the IPP Gerinox performed their delivery contract. Measuring of ports prior to installation is on schedule.
The low-temperature insulation for the plasma vessel is produced by the Deggendorfer Werft MAN DWE. Segments of the thermal insulation for the third module have been mounted onto the plasma vessel. Insulation of the outer vessel has been carried out since September. The design for the thermal insulation of the outer vessel is proceeding. Due to the cramped available space inside the cryostat, the detail design engineering for the thermal insulation and collision control with the neighbouring components has become very time consuming.
Manufacturing of current leads is at the responsibility of the Karlsruhe Research Centre. FZK prepared the production drawings for the prototype of the current lead; thereafter the IPP revised and approved them for fabrication. The final design will be released for serial production after testing of prototypes. FZK procured the high-temperature superconductors needed for the testing of the prototypes. 27 aluminium-steel adapter pieces were manufactured; seven out of them have not been accepted due to geometrical deviations.
The Helium-cryo pipelines inside the insulation-vacuum area of the cryostat supply the coils, the support structure, and the thermal insulation with helium. They are being produced by Romabau (Switzerland). Design and production has been broken down into eight batches. The design of the cryo-piplines for the first module by IPP and the preparation of the production drawings by the company ibk have been nearly finished. Coarse models for the first half of the second module (lot 1 to 4) have been produced. Pipes of the 1st to 4th lot of the first module have been manufactured and delivered. The fixtures for the whole module have almost been manufactured. The design of the pipes and fixtures and the fabrication of all components are still creating bottlenecks. So far the enormous delays in delivery of the pipes and fixtures could still have been compensated by reorganising the assembly process. To avoid further delays design and manufacturing have to speed up.
The company Linde Kryotechnik is proceeding with the completion of the Helium-cooling plant. It has been set up in Greifswald and commissioning tests have been conducted since. Activities for the test programme of the cooling plant control system are proceeding. The test cryostat which is needed for the acceptance of the cooling plant is being manufactured. It will be equipped with a heater to simulate the thermal load occurring during future experiments.
The tendering process for the manufacturing of the power supply for the glow discharge electrodes, which are designed for the cleaning of the plasma vessel, has been finished successfully. The order was placed with Puls Plasmatechnik Dortmund (PPT).
In-vessel components
The Wendelstein 7-X is being equipped with a divertor for energy and particle removal. The heavily loaded baffle plates of the divertor are manufactured from CuCrZr and CFC, which is a material combination that has been proposed for ITER and qualified by prototypes. Only as a start and in order to save time, the components shall firstly be mounted as complete as possible, but then (except for only a few components) operated without cooling (Scenario 3). Instead of the cryo-pumps and the actively cooled divertor an inertially cooled divertor (test divertor unit, TDU) will be installed at first.
The functional specification for the components has been drawn up. The detailed design of the individual modules and their support frames is being continued. One test module has been manufactured and will be tested in the test device GLADIS in Garching. Four different kinds of graphite will be tested to specify the best material. The design of the support frames and adjusting devices has been finished. Activities for the completion of the heat shields and baffle modules are on schedule. Meanwhile MAN DWE has provided 250 wall panels and the process is on schedule. The activities for the cooling water pipeline system for the wall protection are being continued. A manufacturing contract for the manifolds has been concluded. The flexible tubes for the first lot have been delivered and the call for tender for the second lot has been started. Measures for speeding up the process were worked out to avoid risks for deadlines as to assembly of the cooling water pipes, heat shields and baffles in the workshops of Garching.
Heating systems
Microwave heating
Within the framework of a collaboration agreement between IPP and Karlsruhe Research Centre (FZK) concluded in April 1998, the FZK has assumed full responsibility for supplying the microwave heating system for the Wendelstein 7-X. The "Microwave Heating Project" set up for this purpose is coordinating the different contributions from other laboratories and industry. Ten microwave emitters – so-called gyrotons – with a total microwave heating capacity of 10 megawatts at a frequency of 140 GHz in continuous operation are to be made available for plasma production and plasma heating – the worldwide biggest microwave heating system under construction.
The three prototypes have been prepared since then; two of them were designed in Europe together with the French company Thales Electron Devices (TED) and one in the USA at the Communication Power Industries Inc. (CPI). Seven more Gyrotrons were ordered with Thales Electron Devices after invitation to tender.
In contrast to the quality which was proofed during the period of the gyrotron development and for the first serial tube, later produced TED-serial gyrotrons have shown insufficient test results: TED has stopped the experiments at the serial gyrotron SN5. The gyrotron cannot be operated reliably neither with short nor long pulses and was dismounted. Tube manufacturing with TED is interrupted for six months to start a R&D programme with FZK.
Microwave transmission line
The Institute for Plasma Research (IPF) at the University of Stuttgart projects and controls the transmission line which serves for the quasi-optical transmission of microwaves. Their deflection is enabled by special reflectors.
Manufacturing of the new receiver for the grid coupler enabling the simultaneous measuring of the overall performance with a bolometer as well as the mode-selective signal via an optimized horn with successive microwave detector has been completed. The design of the shielding casings between the spires on top of the microwave towers and the torus windows has been continued. The concept for the integration of a directional coupler at the reflectors M 14 has been developed and the stray radiation absorbers in the spires have been designed. Manufacturing of the absorbers in the area of the torus windows have been advanced.
Radio-frequency and neutral-particle heating
Work on the radio-frequency and neutral-particle heating is currently being performed with fewer resources. Nevertheless, the first section of the neutral particle heating, which is designed to produce 10 Megawatt heating output when commissioned, is now under construction.
Assembly
Assembly of the first two half modules on the assembly stands Ia and Ib was duly finalised in March 2008. The second pair of mirror-symmetrical magnet half modules was completed on the meanwhile free assembly stands. Assembly works for the third magnet module which started in September have been continued. The second module is mechanically complete; the activities at the busbar system have started. At the first magnet module the helium piping, the bus system and the instrumentation are being completed. Preparation of the outer vessel shells for the first module has started. The assembly of massive reinforcement fixtures and plasma vessel supports which were mounted for the first time was successful. Considerable efforts are currently being made to facilitate the trouble-free installation of the bus- and helium pipeline system which is more time-consuming than expected. Therefore the assembly of the bus and helium pipeline systems have been parallelised. The delayed delivery of the helium pipeline components shall be compensated by reorganisation of the assembly. The activities for the low-voltage-high-current supply unit and the cooling water supply are being continued according to schedule.
Diagnostics
During the setting-up of the measuring instruments, which will later record the status of the plasma, attention was paid to the diagnostics which will be required to commission the WENDELSTEIN-7X for either supervisory tasks or interpretation of the initial experiments. These include diagnostics for the plasma boundary and divertor, microwave diagnostics, charge exchange neutral diagnostics, spectroscopy for the diagnosis of impurities, Thomson scattering, X-ray tomography, magnetic diagnostics and neutron diagnostics.
Works for the completion of numerous diagnostics are on schedule, however, the increasing shortage of designers is becoming more and more problematic.
Project progress
In the testing device at CEA only twelve coils will have to be tested; the completion of the tests is expected for the middle of 2009. Provision of main components of the cryostat is going according to schedule. Design and manufacturing of the helium cryo-pipes are still critical. Additional resources in terms of personnel for design tasks and collision analyses are provided by IPP. The situation for providing the busbars with suitable supports, fixtures and special clamps by FZJ has stabilised and the deliveries are on schedule. Development and production of components inside the plasma vessel is being executed according to schedule.
Demonstration Cryostat
Cross sectional area of the superconductor
Production of a coil casing (Photo: Noell)
Stellarator coil
Section of the plasma vessel
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