As i said i really appreciate that you have interest in my ETG. It is very ghetto, reason i didnt posted about it before but now that the god of ETG's showed interest in my humble gadget here it is.
Edit: Video link added-->
With the exception of the capacitor bank, it was made from what i had, the tools i had at the time was a drill and some burins, it was made before i had access to machining facilities. One electrode is made of stainless steel and it fits over the plasma cartridge it is held in position by the momentum of a thick steel plate, the other electrode is a 5 mm brass bar with a hole in the center to hold an aluminium bridgewire (.8mm thick), the plasma cartridge is made of nylon, considering i found it offers acceptable performance compared to other polymers also it leaves almost no residue after ablation and doesn't quench the discharge so easily but its difficult to work especially with dull tools, the walls of the cartridge are 4 mm thick and the capillary channel is 5mm diameter 14mm long, the barrel is an aluminium tube 6.12mm ID 30cm long, which i cannibalized from a "cheap" airsoft gun, the barrel is inserted and glued with cyanocrylate to the stainless electrode which is protected by a nylon cap to avoid damage of the glue joint by the shock made by the impact with the steel plate.
Here is a photo of it,
In analogy to yours the propellant consists of an aluminium water mixture, a very fine aluminium powder (20-70 um particle) suspended in water (40/57.5 by weight) with 2.5% carboxymethyl cellulose as gelling agent, i tried pyrotechnic magnalium but it reacts with water alone too quickly. For this particular launcher-power source set, i found the ideal amount of propellant to be approximately 85 mg/KJ.
The capacitor bank consist of 80 450V 680uf electrolitic capacitors, i bought them new relatively cheap ($170) as they are chinese knock off rubycon and nippon-chemicon, the weight variation is almost 50%!, yet they have worked fine so far i m pretty sure i had done more than 200 shots some of them involving inductive loads, the capacitors are connected in parallel series and conform 4 banks which are in parallel, each 800v 3400uf, for a total energy of 4Kj this enables me to have some control of the energy in increments of 25%, all successful shots leaved 370-450V on the capacitor banks.
And now the ugliest of the ugly my glorious Cap bank
(this photo only shows three banks the other was in construction)
Considering how much energy remained in the capacitors i compared the deepness of the bulge made in 16 gauge stainless steel sheet by the impact to the one made by a pellet gun with a measured 22J, i estimate the efficiency to be 15-20%, i estimate velocities of 1500-2000 m/s with .2g BB, every time i tried to launch something heavier than .7g at energies higher than 1.5KJ (effective delivered electrical energy) the glue of the barrel broke or the plasma cartridge exploded.
Here is a capture i took thorough a shade 6 glass while firing the shoot that made the crater of my profile picture, it was 800V 4KJ potential energy 2.2KJ delivered .2g airsoft BB, 350mg propellant. as can be seen there is a really big leak, the cause was a bad union between the breech and the barrel (it was glued
) and it eroded and ruined a good length of the barrel also the muzzle blast is really big and the standoff distance was like 20 cm so it engulfed the target and can't be seen. I tried to color correct the green hue but still it looks really bad so sorry for it, also here you can see the square steel plate that provides inertial confinement to the electrode
Here is the result of that shoot
Here a shoot i did towards putty to compare with yours
Capture of the plasma cartridge shooting to the atmosphere without barrel at 1KJ, the plasma plume measured approximately 70cm, it is really freaking bright this was thorough a 14 shade glass
The most recent photo has a bit more than two years, now i have machining tools so expect something better in the near future also i'm going to buy another 4KJ of the same capacitors soon
, i got noticed that they are available again at the same price. I'm not sure if someone has done it but i got curious to see what happens if such thing hit an higher biological entity so i used an old chicken leg, the smell after that was.. :puke: if someone is curious to see what happened i can send you the link of the photo.I hope you have found my post interesting it is great to see the god of ETG's curious about my achievements!.
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