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Design of the ITER VUV edge imaging spectrometer and R&D for the rotary motional vacuum feed-through
Seon, C.R.,Jeon, J.S.,Cheon, M.S.,Pak, S.,Lee, H.G.,Bernascolle, P.,Barnsley, R. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.1
The ITER vacuum ultraviolet (VUV) spectrometer is aimed at monitoring impurity ion species in plasmas, and it consists of three systems, core survey, edge imaging, and divertor spectrometers depending on positions. In the VUV edge imaging spectrometer, a field mirror and a collimation mirror are used for imaging of the light onto the entrance slit of the VUV imaging spectrometer. To optimize the design of the field mirror box in the ITER port plug, the mirror box mock-up was developed to test installation and alignment. Especially, the mirror alignment using a special tilt stage was tested, and the motional feed-through with a double bellows was developed for the shutter operation. The preliminary qualification test for this rotary motional vacuum feed-through was performed to meet the functional requirement of ITER mechanical feed-through. Leak-tightness for over 15,000 times (larger than operation times) of 360 rotation and backward motion was tested for 1N.m loading condition to the axis rod of the feed-through. In the test, the vacuum inside of the feed-through was monitored, and the feed-through showed good rotation function and leak-tightness during test.
Radiation shielding design evaluation for ITER VUV edge imaging spectrometer
An, YoungHwa,Seon, Changrae,Cheon, MunSeong,Pak, Sunil,Choi, Jihyun,Lee, Hyeon Gon,Bernascolle, Philippe,Barnsley, Robin,Bertalot, Luciano,Krasilnikov, Vitaly,Simrock, Stefan North-Holland 2017 Fusion engineering and design Vol.123 No.-
<P><B>Abstract</B></P> <P>The local radiation shielding design for the detector of ITER VUV edge imaging spectrometer is evaluated based on the MCNP calculation using a local port cell model of ITER upper port #18. A back-illuminated CCD (Charge-Coupled Device), the envisaged VUV (Vacuum Ultraviolet) detector for ITER VUV edge imaging spectrometer will be installed at ITER upper port #18 port cell region, in which a harsh radiation environment is expected with neutron flux higher than 10<SUP>5</SUP> neutronscm<SUP>−2</SUP> s<SUP>−1</SUP> mainly thermalized from d-t neutrons in plasma as well as high gamma ray dose of several tens kGy mainly from <SUP>16</SUP>N isotopes in water coolant. For the evaluation of the radiation exposure to the detector, the local port cell model is developed to reduce both the calculation time and statistical error. The boundary neutron source based on MCNP result using C-lite model as well as gamma source based on ITER radiation map has been utilized for the analysis of local port cell model. Since the radiation exposure to the back-illuminated CCD should be mitigated as much as possible to minimize the radiation damage to the detector as well as single event upset, local shielding design options for the VUV detector with various shapes, thicknesses, and material compositions are evaluated. The result shows that the neutron flux and gamma dose at the location of VUV detector can be mitigated below 100ncm<SUP>−2</SUP> s<SUP>−1</SUP> and 10Gy, respectively, which are the alert thresholds for non-critical electronics in ITER.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The radiation shielding design for ITER VUV edge imaging spectrometer is evaluated using MCNP with a local port cell model. </LI> <LI> The boundary neutron source from MCNP result of C-lite model and gamma source from ITER radiation map have been utilized. </LI> <LI> With proper shielding, radiation at VUV detector can be mitigated below alert threshold for non-critical electronics in ITER. </LI> </UL> </P>
Evaluation of the Neutron Flux Effect on the ITER VUV Diagnostic System in the Upper Port
M. S. Cheon,S. Pak,C. R. Seon,H. G. Lee,L. Bertalot,R. Barnsley 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.3
Because of the harsh neutron environment of ITER, it is important to evaluate the neutron flux effect on the diagnostics, which will be installed near the plasma. A neutron transport analysis on the ITER upper port, which contains an optical system for the vacuum ultra-violet (VUV) spectrometer, is performed for this purpose. Neutron fluxes and spectra at various positions along the VUV optical path, and nuclear heating on the first mirror of the spectrometer are evaluated using the MCNP5 radiation transport code. MCAM, an interface program for the Monte Carlo code, has been used for the conversion of the 3-dimensional CAD model of the upper port plug, including diagnostic module, into the MCNP geometry model. A shutdown dose rate around the port interspace area is also evaluated using the direct-1-step (D1S) method. The result shows that active cooling of the first mirror is not necessary and that the calculated dose rate level satisfies the safety requirement of ITER.
Seon, C R,Hong, J H,Jang, J,Lee, S H,Choe, W,Lee, H H,Cheon, M S,Pak, S,Lee, H G,Biel, W,Barnsley, R American Institute of Physics 2014 Review of scientific instruments Vol.85 No.11
<P>To optimize the design of ITER vacuum ultraviolet (VUV) spectrometer, a prototype VUV spectrometer was developed. The sensitivity calibration curve of the spectrometer was calculated from the mirror reflectivity, the grating efficiency, and the detector efficiency. The calibration curve was consistent with the calibration points derived in the experiment using the calibrated hollow cathode lamp. For the application of the prototype ITER VUV spectrometer, the prototype spectrometer was installed at KSTAR, and various impurity emission lines could be measured. By analyzing about 100 shots, strong positive correlation between the O VI and the C IV emission intensities could be found.</P>
VUV spectroscopy in impurity injection experiments at KSTAR using prototype ITER VUV spectrometer
Seon, C. R.,Hong, J. H.,Song, I.,Jang, J.,Lee, H. Y.,An, Y. H.,Kim, B. S.,Jeon, T. M.,Park, J. S.,Choe, W.,Lee, H. G.,Pak, S.,Cheon, M. S.,Choi, J. H.,Kim, H. S.,Biel, W.,Bernascolle, P.,Barnsley, R. American Institute of Physics 2017 Review of scientific instruments Vol.88 No.8