Linear deuterium Accelerator-Ion Gun Issue

For the design and construction details of ion guns, necessary for more advanced designs and lower vacuums.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Installed the two multi-pin (twenty acupuncture needles per array) collectors in the top dome. I think I will also add a third collector at the peak of the belt/roller as insurance. Of course, keep making adjustments to the assembly since the belt is so close to the edges of the vertical tube (the belt is 10 cm and the tube, where the belt edges enter have just two or three millimeters clearance (ugh.)) Homemade does have its problems since one builds with what one has, rather than the better - that is $$$ - materials.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Quick update: finished the lower emitter electrode array and its support system and made a third upper collector electrode for the dome. Will need to install them; also, I will need to further mod the vertical belt tube system to make better belt/roller alignment; and finally, assemble the high voltage multiplier/polarity power supply. Slowly the very large Van de Graaf is nearing completion.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

The Van de Graaff is done - assembled the last parts and made all adjustments worth doing - runs well; just need to build the high voltage supply for the emitter in order to charge the belt (positive.) Still deciding on the basic design of the voltage multiplier but have all the electrical components. The issue is deciding on the diodes (either 2 amp 30 kV or 0.3 amp 25 kV), which, in turn, will determine the caps I end up using.

Guess I will go with at least a four stage voltage multiplier since that shouldn't cause current issues with moderate caps - want the unit to reach or be in the 30 kV range at least.

Might build a series of HV supplies and just test issues (current/voltage) but in either case, that is the last sub-project before I test the VdG for real - if this doesn't work, I have to admit that VdG's just aren't ever going to cut it - this VdG unit has a 21 inch diameter dome, stands 5 feet 2 inches tall and has a 4 inch belt that is over seven feet long. So it had better produce over 20 microamps above 150 kV; otherwise ... . Well, guess I'll cross that bridge if I come to it.

Will provide some detail pics soon.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Here are some pics of the completed Van de Graaff (VdG). I built the first stage of the full phase voltage multiplier and it worked well - converted the 7.5 kV NST (which is rated 15 kV but is centered taped) and raised it to the full 15 kV positive (full wave.)

The first pic is obviously the VdG; stands 5 ft 2 inch.

The second pic is the emitter electrode array (with the high voltage wire.) This has twenty + pins inbeded in a copper foil within a plexi-glass box.

The final three photo's are different views of the upper collector electrode array. Note the various controls to adjust the belt - these are very fine adjustments and they work very well. A close up of the collector array shows the details of the collector needles. There are two more collector arrays but they are located further down near the base where the belt enters the dome. These are not easy to image.

Until I install the high voltage spray, will not be-able to test the unit. That part of the project is nearing completion. I am building the other three stages now - the first stage used large caps (0.01 mfd, 40 kV and 1 amp 25 kV diodes.) The remaining stages use smaller 20 kV, 4700 pF caps and 0.25 amp diodes.
Attachments
MVC-001L.JPG
MVC-002L.JPG
MVC-005L.JPG
MVC-006L.JPG
MVC-007L.JPG
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Richard Hull »

Very nice machine work and clever use of materials inside the dome. All the best.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Thank you Richard! Hope it works as good as it looks - still, invested only $120 in the unit (not including the voltage multiplier.) Mostly time/effort has been its real cost.

I am partly through constructing the second stage of the voltage multiplier; this is a rather involved project now because I am building it to 1) Be capable of handling three more stages; 2) Be placed under oil to handle the corona issues; and finally, 3) handle large surge currents while having a fast response.

The reason for this significant overbuild of the voltage multiplier (really, two stages - a max of 30 kV is all that is needed - more stages for a VdG would be pointless) is in anticipation of failure of the Van de Graaf current wise (this unit without a multiplier easily reaches over 200 kV); and hence, have a ready 100 kV + voltage multiplier as a backup plan to replace the VdG. Since I have used small diodes/caps in the past with multipliers and obtained terrible results, I decided to build this one with the largest, fast diodes/caps I could reasonably buy without overly committing money (again, a cutoff of under $100 was set.)

I will provide pics of the unit later when it is finished and tested. This single stage, when added to my existing stage, will not require oil since it will only reach 25 kV to 28 kV. After that, oil will be essential if I don't want my current bleeding into the air or hitting me if I get careless (lol.) Since my final load will be in the tens of micro-ampere's I would think a five stage system with big caps/fast diodes could handle that ... I hope. Been wrong before ... .
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

The current output on this Van de Graaf is lacking (current: 3-5 um amps; the voltage was, however, not bad being able to support 20 - 23 cm arc's and was positive) and I will start looking at fixes. A higher voltage spray system for the emitter did not help at all (from 15 kV to 28 kV.) I have some ideas to check but this result is very discouraging considering the units size and careful following of design from a paper by an "expert" - a person who builds these devices routinely and even made a very large VdG for the Boston Science Museum.

As such, I will limit my redesign/fixes accordingly since pay-off is limited unless some significant improvements occur with a few of the more easy changes I envision. Otherwise, with little money invested in this unit, I may follow previous advice and look solely at very high voltage power supplies. Certainly, I will begin upping the voltage multiplier I have with more stages; however, I have little belief it can reach or exceed 100 kV even with the large NST I use. While that system is rather inexpensive, as well, I really think that route will yield insignificant voltage - the electric field needs to be significant to properly accelerate the deuterons along the rather long einzil system I have.

If all else fails, the VdG might barely work if I shorten my accelerator and modify the support structure. These are not fun changes but would significantly reduce current draw. Shielding concerns me (since that too may be a limiting issue but needs to remain in place. Not a simple issue to move that further away.)
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by John Futter »

Dennis
From what I understand from electrostatic engineering the current output from VDG's and Pelletrons is directly proportional to belt width and belt speed
Pelletrons are limited in the width department so parallel chains are used. The optimum belt speed for both is 40MPH (70km/hr).
This belt speed is the trade off point between belt leakage and dielectric absorption timeconstant
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Thank you for the response; certainly, few sites really address belt speed. I am certainly under that speed! May look into upping that.

Did notice that my newly made belt has an aluminum film starting to develop on its inner surface! That is really, really bad. This, I now realize, is due to the roller being designed to center the belt by having a raised central region thus causing this region to move faster than the outer area edges leading to belt slippage (as all Van de Graaff's have to do if their rollers are not flat) and causing wear between the belt/roller surface resulting in my belt becoming conductive (and hence utterly useless!) Using real aluminum tape (as I did) so the rollers do not create their own charge effect and interfere with my power supply/emitter system turns out to an issue. So, I have now removed the aluminum tape from both rollers and removed the belt. Later (after making a new one) I will test the existing "rubber" like rollers and see if they produce a positive "net" current on the dome. If they do, I'll leave them. If not, either I machine my own or buy metal rollers to replace these (not too likely to find ones that fit).

This rather rotten development proves (like I have discovered for a lot of sites on a lot of issues - amazing how much incorrect information has been put out there on just proton guns/accelerators!) that no one who makes VdG's and writes about them has really tried this fix (which so many of them suggest) for non-metal rollers. Had they, they would have noticed this effect immediately and warned people not to go this route! It is getting very old discovering that experts often give untested advice that is counter productive. Pays to only write what one has tested themselves ... .

My belt is history (now) so I will have to make another - may look further into alternate materials than vinyl to see if a better belt could be made since I have to do this. Anyone with experience with belts and would like to comment, please do!

I have considered adding horizontal strips of conductive silver (submicron sized particles into the plastic - will not be solid strips but a conductive paste) on the belt (creating narrow strips separated by insulating belt regions of similar width) to create a more useful charge collecting belt. I am doubtful the work is worth the effort/cost, however. This design would create a belt similar to the metal/ceramic ones used on professional machines and if my VdG works (using a simple belt) I just might do this experiment in the near future.

Will make the new belt next week and test the VdG without the emitter energized and measure the dome's polarity; if positive, I'll measure the current and then test with the emitter to see the net results (if I get higher current.)

If that looks promising, then I will most likely up the motor speed by simply changing the pulley's on the motor/drive roller. That can get me up to 40 mph rather easily.
Last edited by Dennis P Brown on Sun Mar 20, 2016 1:29 pm, edited 1 time in total.
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by John Futter »

Dennis I admire your tenacity
Our Accelerator at work has not had a new belt since 2002 and it runs at 40MPH for 8 hours a day for around 200 days a year that is 896,000 miles or 1,568,000 kms the belt has traveled so far. As far as I know it is made from rubberised canvas and other fillers and is about 3 feet wide and pulley to pulley is around 10 feet.
I will find out the spray voltage and current for you (not to hand at the moment) but very similar to this beast
M&MS_2010_415.pdf
(526.92 KiB) Downloaded 767 times
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

John, thank you very much for the advice and especially the paper. I will read it. I am determined to test ideas/approach (as long as I needed put significant money into the idea) and check results. Discovering that a lot of people out there make mistakes and post without proper testing (ugh!) Still, fun to test ideas but I do desire to make progress at some point!
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Located an inexpensive source of "rubberized" fabric. That is JoAnn Fabrics ( http://www.joann.com/rubber-sheeting-wh ... l#start=10 ) Hope this works but is very inexpensive so worth a try. Cotton backed and white so I assume it wouldn't be conductive (unlike many "black" rubbers since these often contain carbon - or so I have read.)
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by John Futter »

Dennis
I have just looked at our accel.
belt charge 5kV 128uA
Corona stabiliser is @ approx 60uA for 1.9MeV
Column current is approx 70uA

which is close to 130uA total load which equates with the 128uA of belt charge PS the belt also produces charge with out the spray

target current after being through slits and collimators = 22pA
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Thank you John; that really helps me get a handle on issues like no other source has to date. Knowing the current (both applied and achieved) is critical in understanding what is reasonable and what isn't for a Van de Graaff. For me to get over 5 or even close to 10 uamps would be significant considering the value your far larger system achieves (and I bet it is under sulfur hexafluoride (wow, was this first post a funny mistake!)) I can do that for mine (internally only) but the work isn't something I wish to currently perform considering what I still need to do.)

Your post of a real system's actual values tells me a lot about previously published results that simply speculated on their tiny Van de Graaff current. Knowing a viable emitter voltage/current feed also clears up a great deal of confusion for me considering the very few articles that mention this subject at all.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Ordered the rubberized cloth (white; hopefully, non-conducting) for my new belt.

I have a second NST so I will construct a 7.5 kV, full phase and filtered positive supply for my emitter. This should be more than sufficient considering your's.

To play it safe, I am also constructing a 60 ma (max. claim), 30 kV AC flyback transformer system (30-40 kHz) as a possible HV supply for my alternate method to achieve the very HV needed for the accelerator. This will supply my existing voltage multiplier and should achieve the 120 - 180 kV the hard way, maybe. The diodes I have may not support this higher frequency, however. In which case, the 30 kV system still has value.

That is, if the multiplier does fail to achieve the HV due to diode's not handling the high freq, and the flyback system does work (provides the first stage 25 - 30 kV with a current in the 15 - 45 ma range), it can then supply my existing fusor (I do have deuterium gas. Had a registered company # (for SBIR's) when that was still easy to do so took advantage of that.) So constructing this heavy duty flyback system will be worth the effort (again, total cost for this system will be under $100 so in the event of failure, limit my loss. I am able to keep the cost low because: 1) I already have a 15 - 30 volt, 60 Hz, 30 amp power supply for the 2) new, very inexpensive, converter (used to up the 60 Hz frequency to the required 15 - 70 kHz the flyback requires) and 3) the flyback was rather inexpensive.

Finally, as a back up to the back up plan (lol), I did order more of the inexpensive 20 kV diodes just to be ready to try adding more stages to the existing multiplier system; however, that is very iffy with a 60 ma NST (which will not deliver 60 ma under any real load.)
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Well, not much is currently being posted in this section so I will give a short update on progress (or lack there of); the diodes arrived and I have all required HV caps. So could add three more stages to the voltage multiplier (VM) if I desired. Also, have the flyback transformer (allege 30 kV, 60 ma capable - right; give that claim a big laugh) but I still need the 20 volt 60 Hz to 50 KHz converter I ordered. That should get here this week. Will be interesting to see if that works as stated; the unit is just too inexpensive to believe but have been surprised before.

Once I have that converter (I have a big low voltage transformer that can deliver 20-30 volts at 30 amps +, so the converter will have its required power; not that the device needs more than an amp or two), I can then use my existing voltage multiplier system (four stage) to get in the range of 180- 240 kV (very unlikely to get near that high end value but anything over 120 kV would be overkill, anyway so, just hoping.) Since I do not want to increase the voltage multiplier stages due to the extra work (especially the mounting issues requiring oil to work properly) - besides, if the flyback works even close to the mid values, further stages would be a waste of time and just lower the current resulting a less powerful accelerator, anyway.) So, best to wait for the freq. converter so I can test the system (and avoid useless project building.)

If that does not work, then I will add two extra stages to the multiplier and see what voltage the NST will achieve.

Also, even if the flyback/VM system does work I will still test the flyback at some point (no voltage multiplier attached) to see if it can get in the mid to high 20 kV range and output at least 20 -35 ma (seriously doubt the 40 - 60 ma is even possible. The flyback just looks far, far to flimsy to operate anywhere near that level no matter what the company claims.) However, if it does get mid-20 kV and over 20/25 ma then for under $100 it would be a worthwhile experiment; better still, supply my fusor with a higher wattage power supply (current supply is a 28 kV, 15 ma unit - barely acceptable.)

The rubberized cloth company didn't send the proper piece so need to redo that order; so the Van de Graaff project continues to wait.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Quick update.

Had issues with my low voltage, high current DC power supply. Had to gut it and isolate the transformer; then install a diode bridge.

Will have to now use a Varic to control the voltage but at least that power supply does appears to be working again (complex systems do tend to fail as they get old... .)

Hope to test my high voltage flyback transformer this weekend using this power supply with my my new high frequency converter. Be interesting to see what voltage I can get and possibly, measure the current.

If time permits, I guess I will test one of my high voltage diodes to see if it can handle a full 15 kV without failure. If so, maybe test my voltage multiplier to see if the diodes can handle the very high frequency ... be surprised if they do.

Should be a fun, but hopefully not too exciting weekend (as in blown diodes!)
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Wow - a first for me; the high frequency converter had its caps (2) blow up in my face. Guess the DC polarity matters (it is not marked so I assumed it didn't matter - wrong.) That hurt (the debris hit hard even those caps were small)- even at twenty volts the power supply can delivery 4 amps but its ripple cap (for the diode bridge I put in) is 6000 mfd and stores a lot of power. Guess I need a new on (another two weeks to wait.) Really should be marked if it matters but cheap is cheap for a reason, I guess.

The up side is my new power supply works (too) well. It can deliver 20, 40 or 60 volts DC of either polarity. Since it was junk, got it for a few bucks (new, likely over $1000) but I just gutted the electronics (too complex to bother with); installed a new bridge and wired some outputs myself.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Guess I will add a few images for fun. First photo is of the destroyed Freq. converter - one of the two removed blown caps is shown on it side. I think the device needs a proper ground and lack of one allowed the voltage to exceed the rated value of 30 v DC; the power in my ripple cap was just too great so once the voltage margin was exceeded, boom. The last pic is of the PS with both the freq. converter and flyback installed. Hope to get to this point again and actually get it to work properly. Amateurs often learn the hard way and lucky this didn't endup with an injury - respect caps even at low voltage!
Attachments
Destroyed Freq. Converter
Destroyed Freq. Converter
Original Micro-electronics
Original Micro-electronics
Power Supply Panel (stripped)
Power Supply Panel (stripped)
Current PS (no flyback/Freq. Converter)
Current PS (no flyback/Freq. Converter)
Future 30 kV Power Supply
Future 30 kV Power Supply
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Learning from mistakes is slow! Also, doing the reverse engineering to figure out what went wrong and researching the issues discovered takes a lot of time for the electronic illiterate ... . So, as I discovered the hard way, turns out that grounding one side of the transformer and not the diode bridge results in floating the potential of the diode bridge and having the device using the bridge see an "effective" double voltage that a meter does not "see" - end result: burned out ZVS by exploding all caps; also, didn't realize my voltmeter was both low (for reading DC by 25%!) and only reading RMS on the AC side (a new meter does not have either issue.) Result - again, blew up the caps on a new ZVS system.

So, I am again rebuilding the DC 0 - 60 volt (pos)/high current system using these lessons learned - also, the unit will now have a built in voltmeter so I can read applied voltage in real time; further, I decided to install an internal Variac to better allow the system to be controlled accurately and free up the larger variac for other experiments (the non-exploding cap type.)

Most older hands here will be amused by this method of electronics development, no doubt.

Once the new ZVS arrives will try again and hope to avoid exploding caps. If I get this ZVS driver system to work I hope to then try using this to get the well over 100 kV with a voltage multiplier ladder I already have successfully constructed (the 30 - 45 kHz 20-40 volt AC output system will power a flyback for the 30 kV AC I need). Takes 15 days to receive a new ZVS - so, now on my third one already but believe I have discovered/fixed all issues ... . Learning electronics by building devices and experimenting isn't fast - it is effective if one ignores the rather dangerous exploding caps!

On the Van de Graaff front I have obtained the silver epoxy I require - guess I will try and create a belt that has narrow metal strips (horizontal) on its outer face along its entire length to better charge the upper sphere. Hope this approach results in a better total charge.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Well, the power supply works well; 5-8 amps max and 0 - 20 or 0-40, or 0-60 volts DC (can be pos or neg.) Can't believe how much trouble building this was but I did learn a good bit about transformers and diode bridges and issues both about grounding and filtering - as Richard says, build it.

I have been studying ZVS (zero voltage switches) oscillators and if my new one causes problems again (shouldn't since I have a stable and accurate power supply now) I will build my own; turns out I have 90% of the key components it is just a matter of creating a proper circuit board. Making a high current 30-50 kHz low voltage supply using an existing 60 Hz supply is rather easy or so it is claimed (lol.)
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Finish the 0-60 volt DC power supply; realized the issue with the ZVS - it had no marking for the ground and pos inputs which ended up damaging the unit since I didn't know this used polarized caps! So after tracing the circuit determined the correct polarity and realized this was the real issue. Replaced the destroyed cap with a far larger/higher voltage one and replaced a bad resistor. The device works well now.

My flyback is too large for the power supply - 6 amps just isn't enough and the unit tops out at 28 volts creating an extremely low 5 kV from the flyback. Guess I need a better supply - guess I might as well just use my monster 60 - 120 amp, 50 volt transformer (a very big - read heavy - unit. Uses, of course, 220 v)

Glad I am getting some experience with real circuits and able to do some elementary repairs. Also, guess I will hookup my oscilloscope and look at the output frequency later this week.

Below are images of the ZVS freq. converter and a high voltage probe measuring through a HV diode connected to the flyback. Below that image, the entire system.

I installed a variac in the supply so I could free up my large variac. Also, I used a scrap panel meter for the voltage readout; to get it operating I just had to determine the correct resistors to add to get the meter linear over the range. The system works very well (but is, unfortunately, still underrated!)

In any case, this rather long effort resulted in me building from scrap/non-working junk a rather nice variable output pos/neg DC power supply; some interesting theory on ZVS converters and even the chance to repair one. All this just to begin building a alternate 100+ kV supply ...still, learned a good bit (far, far more to go) but has been a rewarding experience through a bit aggravating one ... .
Attachments
MVC-028L.JPG
MVC-027L.JPG
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Hate to preempt the really great post here but just need to update on my accelerator.

I have made a new belt for my Van de Graaff (VdG) - after removing the metal tape on the rollers (caused the belt to short out from getting metal on the inside surface; that was a surprise. Guess the people who recommend that never tried it) - I made a new belt (same plastic material) but have rectangular squares of conductive silver epoxy every 2.5 cm (each about 1 cm "high" and 8 cm wide) along the entire belt (outside only! Otherwise, the same shorting issue would quickly occur!) In this way I have a "metal" link belt without the need to create a chain system (very difficult.) The belt is 10 cm wide so with a 7 kV spray, I hope this belt can charge the dome rapidly enough to create enough current to power the linear accelerator.

Still, pointless to test the unit until I build the room de-humidifier - otherwise, I know the system will short to air most the charge on the dome and prove nothing.

Still, not really counting on this design to work but it will prove the basic idea of the "if" of using a VdG and partly show IF such a thing is remotely reasonable. This is a big unit with a big belt so if it can't work, highly unlikely smaller units - especially commercial ones - will function for this purpose. I am not saying these things aren't good for creating extremely low current high voltage; just that an accelerator column creates too large a current draw for their practical use for this specific application.

IF (and only if) this new design works, will I post both pics and details on construction of the belt.

Backup plan one to this, is installing a neoprene belt on the VdG (no metal) with the rubber rollers - this is considered an ideal belt for creating a positive charge. Again, not convinced.

Backup plan two is to finish the tested and proven voltage multiplier and add the last two stages to get the 120 kV or so; appears to offer a good bit of current. That (see previous posts and images) existing unit is also a rather large monster and needs to be under oil for the last stages to have a chance to develop full voltage. As such, I am holding off on that device final build until the VdG fails.

Really like the previously posted neutron accelerator unit posted here - the VM design they use is a good way to go and most likely, I will end up following that path; I am using a NST since I have big caps and diodes. I did try a ZVS system but it isn't very good (not due to the diodes.) So, will continue with the NST system since it has been very good creating the 50+ kV to date.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Dennis P Brown »

Cautionary tale:

Well, more progress but not bothering to do too much too fast - really, summer is a humid time of year. Recharged the de-humidifier (used propane) and it works great (very easy to do.) The room went from 61% to 32% but that is its bottom - guess long term drying would be required to get below that threshold.

Still, 32%, I feel, is just too humid to even consider running a Van de Graaff much less perform a "make or break" test on this new and very large unit. Need a fair test before I decide what to do.

So, next step is to seal the VdG and use a drying agent within it. Considered SF6 but just not worth the effort. Might create a small enclosure for the entire system (vacuum, ion gun, VdG) so the de-humidifier only drys that smaller space. Combing both is silly so may steal on one this week to be done next weekend.

Bottom line - while building a very large VdG is easy and rather cheap (under $200 for everything) just getting any VdG to operate is tedious and even then, no guarantee that it will work (current wise.) Still, traveled this far so I am determined to finish this project (the VdG) one way or another. Just herding cats isn't a lot of fun ... .
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Linear deuterium Accelerator-Ion Gun Issue

Post by Richard Hull »

A good friend, Bill Richards, an old member of TCBOR here, Now passed away, solved his VDG problems in a unique manner.

He bought a junk hair blower from a local trift store. $1.00 He made a duct/plenum to supply blower air to the column containing the belt. He attachted the dryer to a variac and let it heat the air just enough to be rather dry and warm. Now, this will not assist with moisture in the air around the top load. He would always wipe his oblate terminal with a 90 proof alcohol wet cloth to rid it of dust and lint, (major bleed points). It improved his output by 50% in humid summer conditions and made it spectacular in winter.

Running his VDG always demanded a 5 minute cleaning and de-humidifying prep and another 5 minutes of run before it stabilized.

I own the largest VDG that American Science and Surplus ever made (old Morris and Lee), but haven't run it in years.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Post Reply

Return to “Ion Gun Design and Construction (& FAQs)”