# Embedding Charge in an Insulator

1. Dec 29, 2015

### nlantz

I have been really fascinated with the dielectric breakdown artwork by Bert Hickman seen here.

He is using a 5MeV accelerator to embed electrons in acrylic. He then discharges them to create beautiful fractal patterns. I emailed him last year asking how to calculate the penetration depth of the electrons and he responded that it was depended on the density of the acrylic and the energy of the electrons.
A more specific explanation can be found here.

I am trying to find a way to do this (safely) without renting out a particle accelerator. This is a hobby after all. In order to do this with a CRT for example (~25KeV) I would need a target that has an impossibly low density. About 0.5% the density of acrylic, Even so, this assumes the behavior is linear, and valid, for such low energies. A large assumption indeed.

Has anyone come across a novel way to embed charge densities in an insulator? It could be any charge, It doesn't have to be electrons. It could also be very gradual. Hours or days is OK.

2. Dec 30, 2015

### alw34

3. Dec 30, 2015

### nlantz

I have given this some thought also. If you could make a semiconductor that you could turn on and off the conduction, you could conduct electrons in and then force them to breakdown to get out. It would also need a very low dialectics strength.

I don't think i could build this without a really good materials lab... and 10 years of my life haha

4. Dec 30, 2015

### ZapperZ

Staff Emeritus
Unfortunately, doing a search on "charge density in an insulator" will give you the WRONG concept back, because in condensed matter physics, there is a large topic on "charge density wave". So if you pay attention to the search results, you'll see that a lot of what you got back is related in some way to this topic. This is irrelevant to what is being asked.

Zz.

5. Dec 30, 2015

### ZapperZ

Staff Emeritus
There are several "issues" here if one isn't knowledgeable enough in this area:

1. Doping a semiconductor will not work. What happens when you shoot charges at an insulator is that you are causing charging effects. This means that these charges are embedded into the insulator but doesn't change its structure and composition. The insulator becomes charged. Doping a semiconductor does NOT charge the semiconductor. It remains "neutral" overall. All you are you doing is shifting charge carrier from the dopant to the insulator's band.

2. The original experiment used electrons in the MeV range. If you use a lower energy, such in the keV range, you might easily run into the multipactor/secondary emission range for the insulator. This creates a whole set of problems that you would not anticipate.

Zz.

6. Dec 30, 2015

### Staff: Mentor

Range is not linear with energy, it grows (and goes down) much faster than linear in this energy range.

A beta source can give electrons with MeV energies, but I don't know if the intensity of reasonable sources is sufficient.

7. Dec 30, 2015

### alw34

good, I see you got some posts while I was poking around for any ideas. Take these comments lightly unless they give you a new idea....alas, I'm going to subject myself to ridicule here, I fear!!

I checked out thermionic emission and found Shotkky emission here and some other forms of electron production....seem to be too low a voltage.....I did not check the links to other emissions....

https://en.wikipedia.org/wiki/Thermionic_emission#Schottky_emission

[[Could a radar transmitter or microwave magnetron be modified.....seems like a dead end....microwaves not electrons.....]

I also checked van der graff generators....always liked them....

"A tabletop version can produce on the order of 100,000 volts and can store enough energy to produce a visible spark." still too low.

https://en.wikipedia.org/wiki/Van_de_Graaff_generator

but reading a bit further in the article....'tandem'.......

"...For example, the Brookhaven National Laboratory Tandem Van de Graaff achieves about 30 million volts of potential difference.

The voltage produced by an open-air Van de Graaff machine is limited by arcing and corona discharge to about 5 megavolts. Most modern industrial machines are enclosed in a pressurized tank of insulating gas; these can achieve potentials up to about 25 megavolts...."

I fear too complicated, and too expensive, but should be easier to get access to than a real particle accelerator!!
good luck.

PS: beware 'beta sources' or other radioactive sources....

8. Dec 30, 2015

### ZapperZ

Staff Emeritus
I'm sure you're trying to be helpful, but you are really muddying up the waters here because you yourself have no clue on what you are bringing up. Just because you know how to do a google search, it doesn't mean that you should do a core dump on here to see if something will stick.

And what's with the caution about beta sources and radioactive sources? You can buy SEALED sources for classroom demo, etc. without causing Homeland Security to knock on your door!

http://www.flinnsci.com/store/Scripts/prodView.asp?idproduct=17227

Zz.

9. Dec 30, 2015