FIG. 8. Contour lines representing selected values of the dimensionless heat capacity kernel F*(X,Y,) for a dual-probe heat-pulse sensor with heater probe at (X,Y) = (–,0) and temperature probe at (X,Y) = (,0). The dots show the location of the probes. The numbers on the contour lines are values of P*(,0,), which indicate the fraction of the total spatial sensitivity for the region contained within a particular contour. The fractional spatial sensitivity for each contour of F*(X,Y,) was obtained from Eq. [43]. Table 1 shows the value of F*(X,Y,) for each contour, as well as the area of the region bounded by each contour.