Fig. 7

Plots depicting the (top) ion beam current created from the hydrogen molecular gas with an acceleration voltage of 10.7 keV as a function of the E x B filter electromagnetic coil current and (bottom) the mass per charge of the incident ion as a linear function of the electromagnetic coil current. In the top panel, the blue dots connected with the blue line indicate the measured ion beam current in a unit of \(\mu {\text{A}}\). The top horizontal axis shows the mass per charge calibrated with the linear function in the bottom panel. The red broken line is the sum of two Gaussian functions fitted to the measured beam current. In the bottom panel, the error bar shows the \(1\sigma\) error estimated from the standard deviation of the fitted Gaussian functions. The blue broken line is the calibration line that associates the electromagnetic coil current with the mass per charge of the incident ion constrained with the \({\text{H}}^{+}\) and \({\text{H}}_{2}^{+}\) beam currents