Edge detection of high temperature plasmas Laurence Choi

Edge detection of high temperature plasmas Laurence Choi Sean Burke

Plasmas are all over the place High temperature Often transient Major focus of energy research

UW has 3 major fusion expts. HSX MST Pegasus n n n Short pulse periods Transient instabilities Equilibrium Calculations

Equilibria for stability, Te and Ne Fast (>1 k. Hz) imaging required Mild distortion from lens Two measurments: n n Qualitative Quantitative

Qualitative Fast measurement Preconfigured mask n n n Recalibrate camera adjustments Integrate rows Find max ∂I/∂x

Qualitative Fiducial mark Define coords n CS is R = 0 Draw grid F-th inversion?

Plasma Detection Main Problems n Background (e. g. walls) n Distinguishing edges Methods used n Sobel Operator n Closing n Region Filling n Boundary Extraction

Emphasize Edges Emphasize horizontal edges using Sobel Operator: 1 2 1 0 0 0 -1 -2 -1

Filling in the Gaps Fill in the gaps using the closing operation: dilation followed by erosion: A = Sobel Edges of Image B= 1 1 1 1 1

Removing Background Noise Region Filling Shortcut: in every frame there are regions where we don’t care about the fidelity: paint over in white/black.

Boundary Extraction Morphological Boundary operator used to determine the edges of the plasma. Note that small anomalies still exist.