I must admit that I am not an excellent decision taker. More so when the decision has something to do with my future. throughout my decision taking age (late puberty to present) I have always been extremely confused. I was(and probably still am) confused.

I have always wanted to take up an academic career. If you ask me then it would be my first choice (IF given a choice..ever that is !). To be quite frank, I have not had a single family member (close or distant) who have studied physics at the graduate level at least. there have been some who have researched chemistry but they have either been too distant (quite literally) or too imposing for me. In short, I have never had anyone whom I could look up to.

Except maybe for my mother and my father. My father is an assistant engineer in a thermal power plant. He never had a very solid background in physics. But I did learn quite a bit from him. He made me construct my first motor when I was 9. He also showed me a way I could change it's speed by adding a potentiometer (and old b/w TV volume knob) in series to it. He taught me about series and parallel connections too. But the very best thing that he did for me was buy two classic books for me. He bought for me the two volumes of 'physics for entertainment' by Yakov Perelman and I can never thank him enough for that.

My mother is a housewife. A very sharp and logical housewife!
She has an uncanny interest and knack in physics. Once when I had typhoid, I had to undergo a blood test and while pulling out the syringe from my vein, the doctor spilled a drop of blood on my study table (which no one noticed at that moment). In the evening my mother saw it and tried to rub it off. the stain went away but it left a ring of clotted blood marking the periphery of the stain. My mother asked me the reason behind this ring formation and along with her I developed some sort of a physical theory regarding evaporation and thickness of the blood film at it's various points. Although the theory wasn't in any way extremely accurate, I guess it wouldn't be very wrong if I conclude that my mother gave me the first taste of research (which I thoroughly enjoyed as a child).

But the truth is..I have never had an education in physics. I am just an electrical engineer.

why do i blog? i am not entirely sure. I actually did quit writing long proses back in the 11th class. To be more honest. It was way back in class 10. I have always enjoyed writing. I used to write sometimes to vent out aggression. I even wrote for my own pleasure sometimes. I used to generate imaginary news reports about a certain 'Dr S. Bhattacharya' who has just been declared as the saviour of the world and is being worshipped by everyone. Dr S. Bhattacharya was also revered by the scientific community. And especially the physicists. Since he just discovered the theory of everything along with a fundamental law of nature which had been the missing link all along !

I am surprised when I reflect back on what I used to be and think about what I have become (which I must say isn't radically different from my own naive self about 7 years back :)

It seems to me that each day I look in the mirror. I can find a different me.

and that's exactly why I suppose a lot of guys my age spend 23.33 hrs in front of the mirror every day nowadays. You see..it's technology. Through technology they have been able to read my mind. And now they interprete everything wrongly (sigh) !

dear god..what do I do to save the world NOW !! I am terribly out of practice.

It has been 7 long years since I last saved it (and I even forgot which folder it was in)

trivia!!!!
Such accelerators are scalable to very large applications. By magnetically pulsing a sequence of 64 copper coils in an “atomic accelerator,” scientists have succeeded in stopping a supersonic neon beam in its tracks in the order of a few microseconds. These accelerators can be used for ultra low cost payload launching in the geosynchronous orbit and also as mass drivers in defense applications

some specs you'd need to know

The average muzzle velocity was measured to be 18.43 m/s
Therefore the average muzzle energy is 2.037 joules
The efficiency is 1.48% nearly

Parts you need to build your own launcher !

B1= 9V battery for triggering
C1 and C2= 2200uF 250V capacitor
D1= 800V 10 A bridge rectifier
L1= electromagnetic coil (100mohm resistance, 246µH inductance)
R1= 50 ohm 40watt resistor (charging)
R3= 1 K ohm ½ watt resistor (triggering)
S1= 600V 100A SCR
SW1= push button switch
T1= Variac
R2= 200 K ohm ¼ watt resistor (bleeder/balancing)
D2= 100A free wheeling diode
P1= Ferromagnetic projectile (12 gm weight)

Coil Design
-The most difficult and important part of the design

Factors to be taken into account during the coil design:
1)Inside diameter must fit snugly on the barrel or the firing tube.
2)Outside diameter should be large but must be within the constructional limitations.
3)Coil resistance should be small.
4)Saliency ratio must be high for effective coupling of the electromagnetic field and the Ferro magnetic projectile

For the RLC simulation a RLC simulation program has been used which helped in getting the perfect combination of the voltage, resistance, inductance and capacitance to get the best suited current waveform.


“The best suited current waveform”:
1)Maximum amplitude
2)The one which dies away to near zero in about the time it takes the projectile to reach the mid-point of the coil.

The basic guideline
A charged capacitor is made to discharge itself through this series RLC circuit consisting of the electromagnetic coil. The intention is to make the current delivered by the capacitor to be of very high frequency and amplitude. The discharge is initiated by a small gate pulse applied at the gate of an SCR placed in series with the capacitor. A protection diode, acting as a free wheel, can also be provided to allow the current to circulate in the coil, protecting the electrolytic capacitor from damage.

An electromagnetic linear accelerator consists of one or more coils in the configuration of a LINEAR SYNCHRONOUS ELECTRIC MOTOR which accelerate a magnetic projectile to high velocity

The name Gauss gun is sometimes used for such devices in reference to Carl Friedrich Gauss, who formulated mathematical descriptions of the magnetic effect used by magnetic accelerators. The first such operational accelerator was developed and patented by the Norwegian physicist Kristian Birkeland

We know when current flows through an electromagnetic coil, a magnetic field is produced in its neighbourhood. Here such a coil is made to carry a very high current. This produces a very large magnetic field thus pulling a projectile towards it’s centre. The field is designed to shut off when the projectile is at the centre of the coil.

the beastly bridge rectifier :)
Test Setup 1 ( projectile velocity of around 18 m/s)
THE coil ( made WITHOUT a winding jig :) )
Test setup 2

Here are some of the pictures of the coilgun that I made last year !
Projectile used : an artsy composition made with headless iron nails and feviquick !
Drop me a comment if you would like some technical details :)