RF BD statistics in the TD26CC accelerating structure J. Giner-Navarro 18/11/2014 CLIC Breakdown meeting 118/11/2014J. Giner-Navarro

BD analysis: TD26CC history Data taken for the analysis (at similar conditions): 250 ns conditioning + BDR measurement From 15 th -Nov-2013 to 18 th -Dec /11/2014 J. Giner-Navarro

BD and cell history REF-TRA method to locate breakdowns in the structure. 318/11/2014 J. Giner-Navarro

Breakdown cell distribution Distribution of the BD location for the whole set of breakdowns. Notice the logarithmic scale in the horizontal axis, since events are more likely to happen between less pulses. 418/11/2014 J. Giner-Navarro

Pulses between BDs distribution First 26,000 pulses out Removal of the number of first pulses optimized by chi2 minimization Total 676 BD events BDR = 1.31e-5 bpp I call this subset of 279 BDs the Poissonian data 518/11/2014 J. Giner-Navarro

Pulses between BDs distribution First 26,000 pulses out Removal of the number of first pulses optimized by chi2 minimization Total 676 BD events BDR = 1.31e-5 bpp I call this subset of 279 BDs the Poissonian data 618/11/2014 J. Giner-Navarro Better to see in logarithmic scale

Consecutive BD cell displacement Distribution of cell displacement between two consecutive breakdowns. If next BD was randomly located, we would expect a triangular distribution (red), due to the effect of edges which can move towards only one direction. If we normalize the distribution to be uniform, we see more probability of trigger a breakdown in the vicinity of the previous BD cell. (Poissonian data: first pulses out) 718/11/2014 J. Giner-Navarro

Are the BD clusters also poissonian? It doesn’t look like poissonian, far from an exponential distribution. 8 I call this subset of 397 BDs the pre-Poissonian data 18/11/2014 J. Giner-Navarro

Are the BD clusters also poissonian? Distribution of cell displacement between two consecutive breakdowns. (pre-poissonian data: only first pulses) Same behaviour as the poissonian data: BDs triggered in near cells to the previous one 918/11/2014 J. Giner-Navarro

Correlation Pulses and BD displacement Pre-poissonian data subset. We look for a correlation between the number of pulses and cell location variation between two consecutive breakdowns, to check if BDs within a certain number of pulses are more likely to be closer. This would indicate a debris of the previous breakdown which triggers a new one. Absolute value 1018/11/2014 J. Giner-Navarro

BD Cell displacement? Here we normalize the distribution taking into account that a displacement of 0 cells can come from more cells than a displacement of +28 cells. Then, it seems that it is more likely that a BD is triggered near the previous one when there were less pulses in between. 1118/11/2014 J. Giner-Navarro

Conclusions Data behaves poissonian as we remove clusters separated by less than pulses, to compare with the pulses obtained by Anders’ experiment in the Fixed-Gap system. These figures shows qualitatively that most clustered breakdowns appear near the previous one. Need of statistics and alternative methods to quantify this correlation between the number of pulses needed to trigger a new BD and its location. 1218/11/2014 J. Giner-Navarro