RF, Disruption and Thermal Analyses of EAST Antennas*

Transcription

1 RF, Disruption and Thermal Analyses of EAST Antennas* L. Zhou, W.K. Beck, P. Koert, J. Doody, R.F. Vieira, S.J. Wukitch, R.S. Granetz, and J.H. Irby Plasma Science and Fusion Center (PSFC) Massachusetts Institute of Technology Cambridge, MA, USA Q.X. Yang, C.M. Qin, X.J. Zhang, and Y.P. Zhao Institute of Plasma Physics (IPP) Chinese Academy of Sciences (CAS) Hefei, Anhui, China Oral presentation at 26 th Topical Meeting on the Technology of Fusion Energy, Austin, Texas, USA, Jun. 3, 2015 * This work was supported by US Department of Energy award DC-SC

2 Outline Introduction to EAST antenna analysis models. RF analysis of I and B antenna. Disruption analysis of I antenna. Thermal analysis of I antenna. All analyses are performed by COMSOL V5. F antenna B antenna EAST Port A I antenna 2

3 Analysis Models of EAST Antennas I antenna B antenna F antenna Name I antenna B antenna F antenna Port location in EAST I B F Number of straps 4 2 x 2 4 Overall dimension, width x height x depth, mm Feature 966 x 846 x x 860 x x 906 x 611 Radiation Stripline Antenna (RSA) There are three existing antennas installed on EAST. Analyses will be performed for I and B antenna, mainly I antenna. 3

4 Analysis Type I antenna B antenna F antenna RF analysis Disruption analysis Thermal analysis For each of the three antennas, there are three types of analyses, RF, disruption and thermal analysis. This presentation will not cover all the combinations of the antenna and type. It will show the approach used for each type of analysis and some results. 4

5 FEA Model for RF Analysis of I antenna Whole model Air hidden Antenna itself I antenna Air overall dimension (width x height x depth), mm Plasma major / minor radius, mm Dimensions I antenna 2284 x 2000 x 1933 B antenna 1540 x 2600 x / / 767 Material Properties B antenna Stainless steel 316L I antenna Plasma B antenna Relative permittivity Air Relative permeability Electrical conductivity (S/m) Components I and B antenna are analyzed. The pictures on the left show the FEA model (from left to right): whole model, plasma & antenna only, and antenna only. The table on the upper left side lists the dimensions of the air and plasma. The table on the lower right side lists the material properties used. The approach is to use a diaelectric to load the antenna, but the plasma itself is not of interest for this study. What is of interest is the electric field of the antennas, particularly the component parallel to magnetic field x x Straps and support box 5

6 Numbering of Power Input Ports #1 #3 Strap #4 I antenna Strap #2 Strap #3 Strap #1 B antenna Strap #2 Strap #1 #2 #4 #3 #1 #3 #1 Numbering of power input ports (view from vessel center) #4 #2 #4 #2 Rear view Left: numbering of power input ports while viewing from the vessel center. Middle: I antenna port numbering (view from rear side). Right: B antenna port numbering (view from rear side). 6

7 Electric Field of I Antenna is Within Permissible Level (Port #1 is Activated) 12.9 kv/cm Septum between straps Power input port: #1. Frequency: 50 MHz. Power: 1 MW. Port type: Coaxial. Left: slice plot of magnetic field on XZ plane. It shows the antenna is loaded. Why the antenna needs to be loaded is to study the voltage, magnetic field and electric field of the antenna. Middle: The electric field along Y direction (parallel to magnetic field). Max. is 1.29 MV/m, within the permissible 1.5 MV/m (15 kv/cm). Right: Close-up view of the area where septum has large electric field. Ideally, there will be no cutout on the septum. 7

8 Electric Field of I Antenna is Within Permissible Level (Port #4 is Activated) Power input port: #4. Frequency: 50 MHz. Power: 1 MW. Type: Coaxial. Left: slice plot of magnetic field on XZ plane. Middle: The electric field along Y direction is within the permissible 1.5 MV/m (15 kv/cm). Right: Close-up view of the area where septum has large electric field. Septum between straps When each of the four ports is activated individually, S-parameter is 0.54~0.58. When port #2 or #3 is activated individually, the electric field along Y direction is 0.83 and 0.84 kv/m, respectively, and within the permissible. 8

9 Electric Field of B Antenna is Within Permissible Level (Port #1&2 are Activated) 5.2 kv/cm Power input port: #1 and #2. Frequency: 50 MHz. Power: 1 MW. Port activation: #1 (phase: 0) and 2 (phase: π). Left plot: magnetic field on XZ plane. The antenna is loaded. Right plot: electric field along Y direction (Ey). Max. is 0.52 MV/m, within permissible level 1.5 MW/m (15 kv/cm). 9

10 Electric Field of B Antenna is Within Permissible Level (Port #3&4 are Activated) 4.9 kv/cm Power input port #3 and #4. Frequency: 50 MHz. Power: 1 MW. Port activation: #3 (phase: 0) and 4 (phase: π). Left plot: magnetic field on XZ plane. The antenna is loaded. Right plot: electric field along Y direction. Max. field is 0.49 MV/m, within permissible level 1.5 MW/m (15 kv/cm). When each of the four ports was activated individually, S-parameter is 0.68, the electric field (parallel to magnetic field) is about 0.5 MV/m (5 kv/cm). 10

11 Frequency s Effect on the Electric Field, Y Component Parametric analysis of operation frequencies on the electric field, Y component (Ey) for both I and B antenna are performed. Frequency: 34, 38, 45.6 and 50 MHz. Port #: #1 for both antennas. Left side: I antenna. Right side: B antenna. The smaller the frequency, the smaller the max. Ey (electric field parallel to the magnetic field). 11

12 FEA Model for Disruption Analysis Axial direction (m) #9 Mid-plane #5 #1 #7 #10 #1 #20 #27 #11 #13 #31 #9 #26 #19 Reference: J. Doody, et al., Analysis of new EAST divertor and cooling system during a disruption with halo currents, TOFE 2014, Anaheim, California, USA, Nov. 9-13, 2014, Fusion Sci. Tech. An upward vertical disruption event was simulated, centroid of the plasma moves from 0 to 0.8 m. Left plot: Locations of PF coils (blue) and plasma filaments (red) in the vessel. There are total 14 coils. Only those with odd number are shown here, as those with even numbers are symmetric about the mid-plane. There are total 31 filaments. Air: 30⁰ wedge, radius 4 m. Middle plot: Current of PF coils (max. 2.9 MA) and plasma currents (max MA) from shot # Time is zeroed, for clarity. Right plot: Toroidal field max. 2.6 T at R = 1.2 m. Radial direction (m) 12

13 Stress and Displacement in I Antenna Straps and the Support Box Straps only Straps and box All four straps of I antenna together with the support box is modeled. Left: von Mises stress in the straps.the stress is benign, less than 10 MPa. Middle: von Mises stress in the other components except the straps, within the allowable (yield strength of stainless steel 316L is 290 MPa). Right: Max. displacements of all components. The max. displacement is less than 0.5 mm. 13

14 Electromagnetic Stress in Faraday Shields Screen A Screen B Screen C Screen D Screen A Screen B Screen C Screen D Four Faraday shields are modeled individually. Viewing from the vessel center, starting from left side, they are named A, B, C and D. For each of the shields, there are 43 rods. Total: 172 rods. The top and bottom rod are not included. The stress in the rest rods of the four screens is within the allowable. 14

15 Fluid, Heat Transfer and Structural Analysis of the Strap b) a) c) d) 383 MPa A typical strap (I antenna strap #1, view from vessel center, starting from left side) was modeled. Four plots of the strap are shown. a) Temperature; b) von Mises stress; c) Displacement; and d) Velocity field. Heat load: 0.3 MW/m 2. Water inlet velocity: 2 m/s. Inlet temperature 20 ºC. Results: Max. temperature 424 ºC, below the melting point 2620 ºC; stress in the strap is within the allowable (edge effect ignored, allowable thermal stress 474 MPa). Reference: Q.X. Yang, et al., Mechanical design of the second ICRF antenna for EAST, Fusion Engineering and design, vol. 87, pp , April

16 Fluid, Heat Transfer and Structural Analysis of the Faraday Rod A typical Faraday rod (I antenna, Screen A, middle rod) is modeled. Rod outer diameter 10 mm and hole diameter 6 mm. Four plots of the rod are shown. a) Temperature; b) von Mises stress; c) Displacement; d) Velocity field. Material: stainless steel 316L. Heat load: 0.59 MW/m 2. Water inlet velocity: 2 m/s. Inlet temperature 20 ºC. Results: Max. temperature 258 ºC, below the melting point; Stress in the strap is within allowable (474 MPa). a) b) c) d) 16

17 Summary In collaboration between EAST (CAS IPP) and MIT PSFC, three types of analyses for the existing EAST I port four strap and B port 2 x 2 strap antenna were performed. RF analysis shows that the electric field parallel to the magnetic field for operation frequency of 50 MHz is 0.83~1.45 MV/m for I antenna and 0.45~0.51 MV/m for B antenna, which are within the permissible level 1.5 MV/m (15 kv/cm). For frequencies of 34, 38, 45.6 and 50 MHz, when one port is activated, the smaller the frequency, the smaller the electric field. Vertical disruption analysis of I antenna shows that the max. stress in the straps and the support box of I antenna is 58.3 MPa, and the stress in the Faraday rods (except and top and bottom rod) is within the allowable (yield strength of the material stainless steel 316L is 290 MPa). Fluid, heat transfer and structural analysis shows that the max. temperature for the strap and rods are 424 and 258 ⁰C with heat load 0.3 MW/m 2 and 0.59 MW/m 2 for the strap and the rod, which are below the melting point of the material (2620 ⁰C). The thermal stress of both the strap and the rod are within the allowable (474 MPa). The approach described in this presentation can be applied to F port antenna. Moreover, a field aligned four strap antenna is under design and development in further collaboration. 17

18 Thank you for your time! L. Zhou, W.K. Beck, P.Koert, J. Doody, R.F. Vieira, S.J. Wukitch, R.S. Granetz, and J.H. Irby Plasma Science and Fusion Center Massachusetts Institute of Technology Cambridge, MA, USA Q.X. Yang, C.M. Qin, X.J. Zhang, and Y.P. Zhao Institute of Plasma Physics Chinese Academy of Sciences Hefei, Anhui, China 18