You are here:

Physics/regarding an AC ripple on DC HV power supply


please tell me, regarding an AC ripple on DC HV power supply.
i am doing an experiment to see the best way to release the largest amount of negative air ions from a power source. i have found the usual effect that the curvature is directly correlated to air ionisation. but whilst i have been using a wall power adaptor to convert the AC to DC i found that a noticeable amount of AC ripple might have made it through the transformer all the way through the grounded HV voltage multiplier at 25kV. this i assume because there is an effect that is not inherent to DC; when i use a length of wire instead of a needle as the terminal i have been getting readings that are higher even though the entire wire is insulated and no points are sticking out.
so if this is an AC ripple on the DC i designed an experiment to test this; i used a battery as the power source instead of the wall transformer. the results are as expected; the effect of the long wire disappeared and the needle has a larger outgoing current; ionising the air.
but this made me wonder if i could in fact use the AC ripple/noise in order to increase the ionization that i am trying to achieve. so my question is, if one had an oscilloscope would the ripple be only in the negative part of the negative HV DC or would it extend all the way into the positive (relative to earth). and if it stays in the negative polarity than it is really a negative AC that i have at the terminal and so it still would only produce negative ions, but at a much greater rate than the DC can because the AC makes the wire into an antenna. that is with normal RF AC the electrons just vibrate back and forth but with an of set negative AC entirely in the negative polarity the electrons actually move in one direction (in this case towards grounded objects via the air, ionising the air i the process)?
thank you,

You're referring to negative and positive high voltages, as well as earth.  In fact, this question is full of a lot of statements that make no sense at all.  Can you perhaps clarify with a diagram what you did, one with a circuit showing clearly the setup for using AC, the setup using a battery, and detailing where positive/negative high voltages and ground are?  Only then will I be able to tackle this problem.


All Answers

Answers by Expert:

Ask Experts


Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

©2017 All rights reserved.

[an error occurred while processing this directive]