Carlo Neri

Laser in vessel viewing system for activated areas: mechanical design, manufacturing and tests

A new laser based inspection system (LIVVS) has been developed by ENEA for periodic in-vessel inspection in large fusion machines. The design has been taking into account the radiation levels, operating temperatures and pressures forseen in large European fusion machines such as JET (Joint European Torus) and ITER (International Thermo-nuclear Experimental Reactor). Tests on the LIVVS mock-up are in progress in order to assess the mechanical, optical and electronic performances, and so to measure the system accuracy. Following a detailed mechanical description, preliminary results are reviewed and discussed.

The control and data acquisition system of a laser in-vessel viewing system

This paper presents the dedicated control and data acquisition system (CADAS) of a new laser in-vessel viewing system that has been developed for inspection purposes in fusion experiments. CADAS is based on a MC68060 microprocessor and on-site developed VME instrumentation. Its main aims are to simultaneously control the laser alignment system as well as the laser beam deflection for in-vessel scanning, acquire a high-resolution image and support real-time data flow rates up to 2 Mbyte/s from the acquisition modules to the hard disk and network. The hardware (modules for control and alignment acquisition, scanning acquisition and monitoring) as well as the three levels of software are described.

AM laser system (IVVS) for the ITER in vessel viewing and ranging

Abstract In vessel inspection (viewing and ranging) systems, able to withstand the International Thermonuclear Experimental Reactor (ITER) very severe operating conditions, are fundamental to check plasma facing components in order to properly program ordinary and extraordinary maintenance activities. In this field different schemes have been proposed during the EDA ITER phase each of them showing problems in ranging and/or in radiation hardening and/or in additional illumination source. For this reason ENEA proposed the Laser in Vessel Viewing and Ranging System (IVVS) based on an amplitude modulated (AM) laser beam. At the moment IVVS seems the only system under testing able to perform, at the same time, viewing&ranging under the ITER operating conditions. The IVVS testing is scheduled to be completed within 2002 at ENEAs Frascati Labs. The present paper includes the IVVS design principle and the main results of the optics scheme that is the essential and innovative part of the probe.

Fully Digital implementation of a high dynamic fast Vector Voltmeter

To overcome the analog technology limits a fully Digital Vector Voltmeter has been developed and characterized showing that the apparatus gives better performances than commercial equipment. In particular it can perform measures up to half GHz RF signals, obtaining a phase accuracy up to 0.03° including the linearity error, at output rate of 2 MHz. The apparatus covers a full dynamic range of 80 dB with the accuracy depending on the input level. The apparatus is based on a fixed FPGA Hardware architecture allowing to host different firmware to cope with various applications. In particular the apparatus has been adapted to two different plasma diagnostics of the FTU ENEA Frascati Tokamak: an RF reflectometer and a laser interferometer. Both diagnostics need a difference of phase measure between an IF signal and a reference, but in quite different conditions. The same hardware system has been used for both diagnostics just replacing its firmware to fulfill the requirement of the detection.

A high-data-transfer-rate VME system for TCP-IP remote real-time control of the ITER in-vessel vision system

This paper describes the control and data acquisition system (CADAS) for the in-vessel vision system (IVVS) for ITER, which imposes special design requirements due to its reactor characteristics. CADAS provides remote real-time control of the motors (by TCP-IP), fast data acquisition (20 bytes/pixel at 100 kpixels/s), error management and sustainable network data transfer rates (by TCP-IP). It is composed of a supervisory workstation connected by a 100 Mbit/s Ethernet channel to a remote VME crate, housing a board based on a PowerPC604R CPU running LynxOS, and two on-site developed intelligent modules. The architecture of these VME modules as well as the operation software and the application protocol are described. The test results are presented as well as an image obtained during the test procedures performed at the ENEA-Frascati Laboratory.

The In-Vessel 3D Inspection System For ITER

A prototype of the laser In Vessel Viewing and inspection System (IVVS) was developed at ENEA laboratories in Frascati. The IVVS probe has been conceived and designed to perform sub-millimetric 3D images inside ITER during the maintenance procedure. An amplitude modulated laser radar and an in-vessel scanning head designed to withstand the severe ITER conditions compose it. The paper describes the system and its general architecture, then the characterization phase is briefly described and the main characteristics of the system are reported relating them to the in vessel components and the foreseen operative conditions. Furthermore, the paper describes the new developments still in progress to increase the overall IWS performance and functionality.

Experimental results of laser in vessel viewing system (LIVVS) for JET

Tokamak machines need inspection systems to detect damages on the plasma facing components. The equipment currently in use for in-vessel inspection is mainly based on CCD (charged coupled device) cameras that cannot withstand heavy radiation in vessel operating conditions. To overcome this limit, JET decided to investigate the possibility to replace the actual IVVS TV camera with a radiation-resistant viewing system. For this purpose, ENEA has proposed an amplitude modulated (AM) laser system. Consequently, a new laser-based inspection device (laser in vessel viewing system (LIVVS)) has been designed, developed and tested in ENEA Frascati Laboratories. The system takes in-vessel surface images, scanning the target using a laser beam deflection system installed at the bottom end of a probe, matching the JET mechanical constraints. Experimental results are presented showing the main characteristics of the system.

Status of the design refinement and the characterisation of the in Vessel Viewing system for ITER

The paper describes the key concepts of the In Vessel Viewing System probe in phase of design refinement in ENEA Frascati laboratories and presents an integrated survey both on the design activities and the numerous test activities that have been performed to characterize the system and to verify the compliance of its key elements with the ITER environmental conditions.