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Open circuit ground multiplexing?

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duak:
Quoting above: "... I should probably call the "ground plate" a return plate because it isn't always grounded, rather, it is usually floating with no potential until it is connected to ground to induce the ion transfer.  Current only flows through the single return plate that is presently pulled low to ground potential.  All of the other return plates are open circuit."

Unless there is something I don't know about, I don't think that things work this way - there won't be any plates that won't have a voltage on them in the range of 0 V to 4 KV.  The solvent exits the HV plate with a charge - you mentioned ion transfer in the first post.  The charged  solvent is drawn towards whatever objects have some voltage that is lower the HV plate and when they reach it, deposit the charge from the ions.  If that plate is grounded, the circuit is complete and a current flows.  The other plates initially have a voltage - they can't avoid it.  If they are high impedance,  the solvent will deposit a charge until its voltage reaches the same as that of the HV plate.

The problem is that this voltage will be up 4 KV and that any switch or other device or component has to be able to withstand this voltage and not conduct significant current.  Any conduction will drain off the charge and reduce the voltage until an equilibrium is reached.

There may be an out here.  What is the relationship between plate current  and plate voltage? Is it linear or exponential?  Is there a threshold voltage needed before any current can flow?  Is a minimum voltage required to sustain current flow?  If so, then it may be possible to use lower voltage devices.

When I google "electrospray ionization" I get something that has only one receiving plate and an aperture for the ionized samples to pass through.  I don't see multiple receiving plates each with a selective attractive voltage.

Perhaps the two functions could be separated.  An outer ring that is grounded to attract the ions or charged to 4 KV to not attract them and an inner electrode that is essentially grounded by the multiplexer and attracts and collects any ions that get by the outer ring.

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