Fusion Programme - ENEA - Fusione

Fusion ProgrammeRange (mm)59358357356377 MHz sigma = 290 μm193 MHz sigma = 125 μmFig. 3.24 - IVVS performance improvement achievedby increasing laser beam modulation frequency fromf m =77 MHz up to f m =193 MHz. Comparing distancemeasurement accuracy σ (defined as inverselyproportional to standard deviation of the distancemeasurements) an improvement factor of >2.3 isexperimentally obtained5531 101 301 501 701 901Pixelswith interferential filter σ = 0.834without interferential filter σ = 0.387Fig. 3.25 - IVVS performanceimprovement achieved by removinginterferential filter (f mod =193 MHz,stay time per pixel 20 μs) duringtesting on ITER FWP mockup. Noisereduction (inversely proportional toaccuracy) is evident. Standarddeviation of ranging measurementsis reduced by a factor of >2, whichindicates an equal improvement inmeasurement accuracy270.7mm220.7533.0 pixels630.0 pixels350.0mm300.0570.0 pixels639.0 pixels2007 Progress Report56Fig. 3.26 - Total improvements inIVVS. Experienced performance usingITER full-scale mockup of the ITERDVT “carbon”. As an example,measurements on DVT carbon blockwith 30° of beam incident angle areshown. It can be noted that:• with the 2006 IVVS (black line)performance, most measurementsshow an accuracy of about 5 mm,while the best performance is about1 mm;• after the 2007 improvements(orange line), all measurements showan accuracy better than 0.5 mmCounts100000100001000100IVVS 2006performancec_OLD carbon_30°c_blk_80°c_blk_70°c_blk_60°c_blk_45°c_blk_30°c_blk_0°IVVS improved performance10010 100 1000 10000Amplitude (max 65535)9753Sigma (mm)[3.13] L. Petrizzi et al., Fusion Eng. Des. 82, 1308 (2007)[3.14] B. Esposito et al., TW6-TPDS-DIADES ProcurementPackage 11 – Radial Neutron Camera and EquatorialVisible/IR Wide Angle Viewing System, ENEAcontribution to First and Second IntermediateReports on TW6-TPDS-DIADES (2007)