Tuesday, December 27, 2011

why so serious?

For some time now, and as previously reported, I have been unable to make much headway on any of my Mad Science projects. There are various reasons for this, some good, some not-so-good.

Here are some good ones:

* I've been unemployed since May, and every single project needs parts which must be purchased. Many of said parts are relatively inexpensive, but there has been NO disposable income until recently, and that due solely to the generosity of friends. More on this down below.

* my wife just went through total hip replacement surgery. If you're not familiar with that, please take my word for it that it is brutal and very challenging to recover from. This will be the third such surgery she has endured. Recover takes months, happens at home, and I am all of the nursing staff (poor girl).

* I've got health issues of my own which are severely hampering my ability to do what I'd like to be doing. I'll spare you the details.

And now the good news: I start a new job in January and should have paychecks coming in mid-month.

I've also been honored to receive an honorarium / stipend / fellowship from The Joss Research Institute, a private R&D firm in Maryland. It came with some funds which for now went into paying bills, but which will be pulled back out of my future paychecks and earmarked exclusively for expenditure on my science projects. I think it is entirely appropriate that said money be used exclusively for that, especially given the spirit in which it was given, which was to help remove obstacles to my getting shit done. It's also easy to do this since our credit union gives us several free accounts to stick money into for various purposes.

I have to say, I am quite flattered given the smarts of the guys who gave it to me. We all communicate with several other folks with similar and branching interests along the lines of pulsed power, high voltage, high vacuum, physics experiments, lasers,

To make this post a little better than a place-holder, I offer the following:

My Triggered Spark Gap Switch requires some rework before I strap it to one of the 3kJ pulse caps and a pulse resistor and transfer a 1 kA / 1MW pulse through it.

It turns out I can do at least part of said re-work without spending money. I just need to get a different project off of the lathe so I can work on the trigger plane electrode. Two things need doing:

Thing One
I'll be making the ID about twice as large, all the better to pass a large diffuse plasma discharge, my dear, preferably without actually involving the trigger electrode - remember, this is a field-distortion switch, we hope)


Thing Two
I'll be removing the radius on the ID, leaving instead an acute angle with a sharp edge. This angle will be tapered on the large-gap side and in-plane on the small-gap side. The better to distort the field with, my dear. However, a sharp-edged trigger plane must be PREZACKLY biased with respect to the ratio of the two gap distances. I have the vague recollection that the ratio of diameter to main electrode distance was to be in the range of 1.0 - 1.6, but my memory is notoriously unreliable, so we'll just leave that a hypothetical until I find the collection of photons and spins states that constitutes a "white paper" these days...

Looky here:

switch tear-down.jpg

That brass disk with the hole in it, bottom-center, is the trigger plane electrode. The hole in the middle needs to be about twice as big or a bit bigger. Someone mentioned (in some switch white paper I have somewhere) an empirically-arrived-at rule of thumb for main electrode distance vs. hole size for this style of switch, but finding it again will take some time...

As is probably obvious, this switch has not had a single shot through it. I realized after I finished it that the changes were needed. Just now got around to diddling with it in between thirteen other things.

I lied unintentionally: THREE things need doing. A second set of holes in each switch end plate needs to be made, identical to the ones that are there now, but countersunk in the opposite direction, for bolting the switch into a transmission line or to coaxial test loads. Having a bolt circle lets me fashion large-diameter connections and current paths which translate in the general case to low distributed inductance, which informs the minimum attainable pulse rise time. Readers who have read my earlier descriptive material here and on Flickr will have gleaned that a big part of what I am hoping to do with this switch is not merely transfer big lumps of energy around, but to achieve very fast switching speeds and commutation times -- fast, that is, for a rank amateur with not formal schooling in pulsed power!

Oh yes, I will be studying calculus in 2012, or that's the plan anyway.

I'm just not in any shape to finish the project currently occupying the lathe and which I don't want to re-center later. Humph. But I am not idle. I'll get some of the above done soonish I think. Things ought to be a LOT better in 2012 than they have in a very long time.

Stay tuned.

1 comment:

jodys said...

It is really neat to hear about the stipend/fellowship! Good luck with calculus, too! Serious offer: if you need any help (which you probably won't), let me know. I have a pretty light school schedule this spring and summer.