A charge-imbalance-sign cross-scan flips the sign of the test charge across rows, showing how the shielding cloud pulls in opposite charges in either case while the visible response mirrors the sign. The arithmetic is exact only for the stated signs, charges, and rows in the ideal shielding model. Real plasmas add collisions, sheath boundaries, nonuniform density, temperature spread, diagnostics calibration, and measurement/source uncertainty.
Net charge sign is scanned across ion and electron counts. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Net charge is a count difference
The checked source has one more ion than electron, so the finite charge ledger is positive one coulomb.
5⋅1+4⋅(−1)=1C
Adding or removing one charge flips the sign
The middle row has excess ion charge. The last row has excess electron charge. The neutral row has equal counts.