I wanted a source of 10^4-10^7 elementary charges to test a diagnostic (Faraday cup) for the ion trap.   It turns out charging an insulated metal plate with a small voltage (2.5V and 0.25V shown here) leaves enough static electricity on it to produce this small charge!
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<br />I triggered the scope on the small "shark fin" that appeared when I touched the probe to the plate and the charge drained through the scope's 1MOhm resistor.   It can even integrate the area.   For 0.25V applied, the area was 3.2e-6 V.s, corresponding to 3.2pC of charge, or 2×10^7 electrons.
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<br />To get less, I would apply even smaller voltages to smaller plates, although the main purpose of this is to test an amplifier that will boost the signal.
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<br />#physics #accelerators <p><a href='posts/202607/post-20260702-194619-a.jpg'><img src='posts/202607/post-20260702-194619-a.jpg' loading='lazy' /></a></p><p><a href='posts/202607/post-20260702-194619-b.jpg'><img src='posts/202607/post-20260702-194619-b.jpg' loading='lazy' /></a></p><p><a href='posts/202607/post-20260702-194619-c.jpg'><img src='posts/202607/post-20260702-194619-c.jpg' loading='lazy' /></a></p>