Application Exploration of Avogadro Constant-Level Precision in Electron Microscope High-Voltage Power Supplies

In the fields of nanotechnology and materials science, the resolution and analytical accuracy of transmission electron microscopes (TEM) and scanning electron microscopes (SEM) depend directly on the stability of the electron beam acceleration system. As the core component of electron acceleration, the high-voltage power supply (HVPS) has its precision level become the key to breaking through the bottleneck of atomic-level observation. Avogadro constant-level precision (on the order of 10⁻²³) means that the fluctuation of the power supply's output voltage must be controlled below the microvolt level, and this indicator is decisive for electron microscopes to achieve single-atom imaging and accurate elemental analysis.
From the perspective of technical implementation, the electron microscope HVPS needs to overcome three core challenges. First, ripple suppression and electromagnetic compatibility. During electron acceleration, power supply ripples cause fluctuations in electron beam energy, which in turn leads to blurred imaging. By adopting a multi-stage LC filtering and metal shielded cavity design, high-frequency ripples can be suppressed to below 1μV, while isolating electromagnetic interference between the electron microscope chamber and the external power grid. Second, temperature drift compensation. The parameters of internal components of the power supply (such as high-voltage modules and sampling resistors) change with temperature. It is necessary to integrate a high-precision platinum resistance temperature sensor and combine it with an adaptive PID algorithm to real-time correct the output voltage, controlling the precision deviation caused by temperature drift to within 0.1μV/℃. Third, load dynamic response. When the electron microscope switches imaging modes (e.g., from bright-field imaging to dark-field imaging), the electron beam current changes abruptly. The power supply must complete load adjustment within 100ns through a high-speed sampling chip (sampling rate ≥1GS/s) and fast-response power devices to ensure stable voltage without overshoot.
In practical applications, HVPS with this precision level significantly improves the performance limit of electron microscopes. In TEM single-atom structure observation, the stable acceleration voltage reduces the fluctuation of electron wavelength (λ=h/√(2meU)) to less than 0.001pm, with imaging resolution breaking through 0.5Å, enabling clear capture of atomic arrangement defects. In SEM elemental analysis, the energy deviation of characteristic X-rays is controlled within 0.1eV, and the accuracy of elemental identification is increased to 99.9%, effectively distinguishing subtle content differences of light elements (such as C, N, O). In addition, in the field of biological electron microscopy, the low-noise and high-precision power supply can reduce radiation damage to biological samples, extend observation time, and provide more reliable data support for virus structure analysis.