Fig. 1. (a) Schematic of the VMMXS system. (b) Simulated electron beam trajectories for the VMMXS with the positive grid value. (c) Simulated electron beam trajectories with the negative grid value.

Fig. 2. (a) Optical photograph of the full VMMXS assembly. (b) X-ray energy spectra of the tungsten target. (c) Photon counts versus cathode power consumption characteristics of the VMMXS. (d) Photon counts versus grid voltage characteristics of the VMMXS.

Fig. 3. Pulsed width and modulation rate of the x ray are controlled by modulating the grid electrode.

Fig. 4. (a) Photon counts versus the grid pulse frequency characteristics of the VMMXS. (b) Photon counts versus grid pulse frequency contrastive characteristics between the former one and the new one. (c) Anode current versus grid pulse frequency contrastive characteristics between the former one and the new one.