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The ITER ECRH system consists of 24 gyrotrons with up to 24 MW installed millimeter wave heating power at 170 GHz, power supplies, control system, transmission lines, one Equatorial and the four Upper Launchers. With its high frequency and small beam focus the ECRH has the unique capability of driving locally current. While the Equatorial Launcher mainly acts for central heating and current profile shaping, the Upper Launchers aim on suppressing MHD instabilities, especially neoclassical tearing modes (NTM) triggering plasma disruptions. The Upper Launchers inject millimeter waves through a quasi-optical section consisting of three fixed and the front steering mirror set. The eight overlapping beams have focal points optimized for suppression of the q = 3/2 and q = 2/1 NTMs., Several project change requests required the redesign of the Upper Launchers and the connected ex-vessel system. This redesign includes a new boundary geometry of the launchers as well as a newly designed cooling system for the Blanket Shield Module (BSM), a modified flange of the BSM to the structural main frame and a refined optical design. Additionally shield blocks with integrated in-vessel waveguides were added and the closure plate with waveguide and supply line feedthroughs was adapted. Further changes, not all caused by PCRs, include newly designed ex-vessel waveguide components with a reduced aperture and redesigned ultra low-loss CVD diamond windows. Finally several components originally foreseen as off-the-shelf components have become part of the design scope. The new launcher design status is presented with selected results on numerical design validation.

New optical configurations for the ITER core CXRS system offer the possibility of longer ducts between the first mirror and the plasma. This has led to a renewed optimization of the availability. using a simple model of the degradation of the first mirror that starts with the conditions of (a) the required measurement performance and (b) the geometry of the port plug. It is found that for a fully passive system the design should strive for the longest duct length possible. Given known data, this will result in a diagnostic lifetime still substantially shorter than ITER lifetime. When an option of cleaning the first mirror is introduced (assuming this is a feasible option) the optimum is less straightforward, because the lifetime of the second mirror then also becomes important. The optimum then depends on the ratio between the cleaning interval and the ITER lifetime. Options are presented for various sets of assumptions. Finally practical limitations of supporting subsystems (cleaning system, shutter, calibration system) may influence the final design. Examples of such limitations with their impact are presented. (C) 2011 Published by Elsevier B.V.

The upper port #3 in ITER will be used by the core Charge Exchange Recombination Spectroscopy (core CXRS) to channel out light from the inside of the vacuum vessel. Recent research about the lifetime of the first two mirrors and changes in the upper port plug geometry initiated further investigations into possible alternative system design concepts. Two new variants of the optical system were chosen for further investigation. The different sub-systems of core CXRS such as optical system, retractable tube and shutter are introduced together with their impact on the system design and their interactions. Space constraints originating from the envelope of the UPP and requirements emerging from the ITER environment such as remote handling and other maintenance considerations are also included in the investigation. Alternative system concepts taking the constraints into account are presented and discussed. Implications for further design work on the subsystems are derived from the results. (C) 2011 Forschungszentrum Julich, Association EURATOM-FZL. Published by Elsevier B.V. All rights reserved.

Central, retractable tubes are proposed in several Upper Port Plugs (UPPs) designs for ITER, to enable fast exchange of specific components of diagnostics housed in these UPPs. This paper investigates into possible designs to enable the efficient handling of tubes. The feasibility of tube handling is analysed by first reviewing the designs drivers. Several concepts for handling of the tube are proposed, exploring the limits described by the design drivers. Suggestions are presented for tube integration into the UPP design, concerning the tube mounting into the UPP, the load takeover and coping with the thermal elongation. It is found that the handling of tubes is feasible but still requires a lot of system level integration. Also, the added value of a tube as a feature in an UPP design to the availability of the subsystem the UPP is a part of, is questionable and needs further assessment on ITER system level. (C) 2011 Elsevier B.V. All rights reserved.

The paper presents component concepts developed for the ITER core charge exchange recombination spectroscopy (cCXRS). They are based on the cCXRS layout of 2009, named as reference design option. It includes an outer shell, carrying a blanket shield module and a shielding cassette. The cassette, attached to the outer shell, carries secondary mirrors and a retractable tube. The tube holds a first mirror (M1) and a shutter. Development priority is given to the M1, M1 holder, shutter, calibration system and retractable tube. These units are the most critical from reliability point of view. The developed design approaches could be likely used as generic or prototype solutions for a cCXRS diagnostic port plug in future. Before prototyping critical components as the M1 holder and shutter, the final cCXRS conceptual design has to meet forthcoming changes in the ITER diagnostic upper port plug (UPP) and blanket system. The integrated first wall diagnostic shield modules, first wall recession, blanket shaping and generic UPP layout have considerable impact on the layout of the cCXRS and its components. The paper presents a preliminary solution for integration of the customized reference cCXRS into expected ITER blanket and UPP layouts. (C) 2011 FORSCHUNGSZENTRUM JULICH GMBH-EURATOM-FZJ. Published by Elsevier B.V. All rights reserved.

A plug for the ITER core charge exchange recombination spectroscopy (core CXRS) is located in the upper port 3. It transfers the light emitted by interaction of plasma ions with the diagnostic neutral beam (DNB). The plug consists of a main shell, a shielding cassette and a retractable tube. The tube carries the first mirror (M1) with a shutter and allows multiple replacements of M1. A large uncertainty in the M1 lifetime has initiated a new design option with M1 located as far as possible from the first wall. A fast shutter has been proposed to enhance M1 protection. It operates consistently with a pulsed DNB and uses elastic hearings. Three-point attachment scheme of blanket shield modules (BSMs) has been suggested. It is capable to react electromagnetic loads caused by eddy- and halo-currents for any BSM option with a good design margin. The concern has been raised with regards to the forces caused by halo current and applied to the entire plug. Possible solutions are either to shunt and support the plug to the port in the frontal part, or re-attach all BSM in this belt from the plugs to the vacuum vessel. (C) 2009 Elsevier B.V. All rights reserved.

All ITER sub-systems of remote handling (RH) classes 1 and 2 have to be remotely maintainable. The maintenance strategy for these components has to ensure system availability after failure or scheduled maintenance. This paper shows how virtual reality (VR) simulation [1] can be used as a tool to analyze the maintenance process, to predict the mean time to repair and to ensure the RH compatibility of one ITER sub-system, the Upper Port Launcher (UPL) [2]. Special emphasis is put on the development of RH procedures and the identification of tooling requirements. The possibility to Simulate RH logistics and repair actions in an early stage of the design process allows for the identification of those maintenance actions that require dedicated tests in the Launcher Handling Test Facility at Karlsruhe. The VR analysis. together with dedicated mock-up tests will demonstrate the RH compatibility of the UPL plug, provide input to the design of the Port Plug maintenance area in the ITER Hot Cell, and support the development of RH maintenance tooling. (C) 2009 Published by Elsevier B.V.

Already in the early phase of a design for ITER, the maintenance aspects should be taken into account, since they might have serious implications. This paper presents the arguments in support of the case for the maintainability of the design, notably if this maintenance is to be performed by advanced remote methods. This structure is compliant to the evolving maintenance strategy of ITER. Initial results of a Failure Mode Effects and Criticality Analysis (FMECA) and a development risk analysis for the ITER upper port plug #3, housing the Charge Exchange Recombination Spectroscopy (CXRS) diagnostic, are employed for the definition of the maintenance strategy. The CXRS upper port plug is essentially an optical system which transfers visible light from the plasma into a fiber bundle. The most critical component in this path is the first mirror (M1) whose reflectivity degrades during operation due to deposition and/or erosion dominated effects. Amongst other measures to mitigate these effects, the strategy is to allow for a replacement of this mirror. Therefore it is mounted on a retractable central tube. The main purpose of this tube is to make frequent replacements possible without hindering operation. The maintenance method in terms of time, geometry and spare part policy has a large impact on cost of the system and time usage in the hot cell. Replacement of the tube under vacuum and magnetic field seems infeasible due to the operational risk involved. The preferred solution is to have a spare tube available which is replaced in parallel with other maintenance operations on the vessel, as to avoid any interference in the hot cell with the shutdown scheduling. This avoids having to refurbish a full port plug and also allows for a more frequent replacement of M1, as we can replace the mirror anytime the vacuum vessel is vented, estimated to be once a year. (C) 2009 Elsevier B.V. All rights reserved.

The ITER core charge exchange recombination spectroscopy (core CXRS) diagnostic system is designed to provide experimental access to various measurement quantities in the ITER core plasma such as ion densities, temperatures and velocities. The implementation of the approved CXRS diagnostic principle on ITER faces significant challenges: First, a comparatively low CXRS signal intensity is expected, together with a high noise level due to bremsstrahlung, while the requested measurement accuracy and stability for the core CXRS system go far beyond the level commonly achieved in present-day fusion experiments. Second, the lifetime of the first mirror surface is limited due to either erosion by fast particle bombardment or deposition of impurities. Finally, the hostile technical environment on ITER imposes challenging boundary conditions for the diagnostic integration and operation, including high neutron loads, electromagnetic loads, seismic events and a limited access for maintenance. A brief overview on the R&D and design activities for the core CXRS system is presented here, while the details are described in parallel papers. (C) 2011 Elsevier B.V. All rights reserved.