Electromagnetic Crusher



Crushed cans
Aluminum cans shaped by Electromagnetic pulse.

Next : shrinking money.
Same financial effect as the Y2K stock market but with purple fire and thunder.

sparx 3
The Crusher

Electromagnetic Metal Forming

Intense Electromagnetic pulse fields can shape metals. Used in aerospace since 1961, "magneforming" technology is a non-contact method to form metals by magnetic pressure created by opposing magnetic fields in a work piece and a work coil. When an energy storage capacitor bank is switched into the work coil, an intense magnetic field is created which rings at the system resonant frequency, typically 5 - 50 kHz. An induced current and corresponding magnetic field in the work piece oppose the original field, creating a magnetic pressure. Maximum magnetic pressure during the first quarter cycle can exceed 50,000 psi during a few tens of microseconds, causing the metal to yield at speeds exceeding 1000 ft/s.

bar

! ! WARNING ! !

This device involves extreme voltages, possibility of fire, explosion, violent ruptures of components and other risks.

 


Construction of such devices may be illegal in your area.
You could be hurt. You could die.
Take cover. Turn it on.
Fear what you have created.

bar

High Voltage

Click Hazard Icon For More Info

 

This device involves very high voltages.

bar

PCBs

Click Hazard Icon For More Info

 

Don't Die Like a Poisoned Roach ! Test For PCBs in old High Voltage components !

bar

Altair's Electromagnetic Crusher

Mk I Crusher Schematic Diagram

Mk I Crusher Schematic Diagram. The left half is the charging system, the right half is the Theta Pinch Machine.

The charging section, left, consists of a high voltage transformer driving a Cockcroft-Walton multiplying rectifier, producing up to 70 kVDC. The Theta Pinch Machine, right, consists of a capacitor bank, a discharge switch, and a work coil. The work coil will typically be destroyed, and a new one is fabricated for each test.

Mk I Crusher Construction Pictorial

Mk I Crusher Construction Pictorial

Theta Pinch Machine - The Capacitor Bank

Mk I Crusher Trolley

Making a wooden trolley to hold the capacitor bank. The capacitor bank is mounted so that one end can be elevated to 100 kV without flashover.

Mk I Crusher Capacitor Bank

Capacitors standing in trolley. 2 each 0.4 uF at 100 kV in parallel. Energy = 4000 Joules at full rated voltage. These surplus capacitors are plastic cased and oil filled. There was slight mechanical damage and oil leaks. The tops were drilled to allow topping off with clear mineral oil.

Mk I Crusher Construction Parts

Use BIG connections. 1 inch copper pipe can be crushed onto 3 in wide tinned copper braid to make heavy duty lugs. Cables must be anchored firmly against thrashing due to magnetic forces at the moment of discharge.

Theta Pinch Machine - The Switch

Mk I Crusher Construction Parts

The discharge switch has two contacts, one moveable. What kind of cheep contact can take this much punishment ?!? How about those old steel trailer balls with the stripped threads... solder 'em to copper pipe.

Mk I Crusher Construction Parts

Other parts : Tinned copper braid, 3 inch wide with crushed copper pipe for terminal lug. Corona balls = brass doorknobs with 1/2 in nuts driven in and soldered.

Mk I Crusher Construction Parts

Clean, dry, virgin PVC is a good insulator. The switch body, top, is a 4 inch PVC pipe. On the left is a closet flange and reducers to hold the fixed electrode. On the right, a PVC flange and PVC collar are connected by a 3/4 in PVC pipe that keeps the moving electrode centered while allowing it to travel axially.

Mk I Crusher Construction Parts

The assembled switch must be thoroughly deburred, clean and dry. The switch body should be so clean it 'sizzles' with static electricity when wiped down with a clean paper towel. The contact separation is 9 inches when the switch is open, and one inch when the switch is closed.

Mk I Crusher Construction Parts

The work cell is attached to the fixed contact of the switch. The work coil and "victim" will be installed here.

Theta Pinch Machine - The Work Coil

Mk I Crusher Work Coil

The Work Coil performs work on the test object. At high energies, the Work Coil is used one time only. Beware ! The Work Coil is subject to EXTREME MAGNETIC FORCES and CAN VIOLENTLY DISINTEGRATE at the moment of discharge. In accordance with Lenz's Law the Work Coil experiences magnetic hoop stress in axial compression and radial expansion, possibly leading to violent rupture of the conductor. Above 1000 Joules a lexan blast shield is needed. Above 4000 Joules you need heavy metal. At high energies, fragments of the Work Coil are accelerated outwards exceeding the speed of sound. Dont get killed by shrapnel.

Charging System - Power Input and Main Transformer

Mk I Crusher Transformer

The mains transformer, T1, is a 70:1 potential transformer. With 240 VAC input, it produces 16.8 kVAC out. Thats rms voltage, so the peak transformer voltage is 23.5 kV.

Charging System - Multiplying Rectifier

Mk I Crusher Raw Diodes

Five rectifier stacks are used, D1 thru D5. Each rectifier stack consists of 12 modules in series, FairRadio #1540/ARC58. Each module consists of ten Raytheon type 1N1095 silicon rectifier diodes in series, each rated 500V 0.75A, plus five series capacitors in parallel with the diodes, each 0.001 uF @ 1kV. The charging section contains 5 stacks of 12 modules of 10 diodes for a total of 600 diodes. The peak transformer voltage of 23.5 kV gives a maximum charging system output of about 70 kV.

Mk I Crusher Raw Diodes

Each FairRadio #1540/ARC58 rectifier consists of 6 strips of ten diodes each, arranged in a three phase fullwave wye bridge. The bridges are cleaned, dried and disassembled into individual strips. All metal studs are removed from the nylon spacers. The top covers are sawed into thirds to make more insulating blanks like the ones originally sandwiched between the diode strips. Endplates are made from the bottom covers, sawed down by one third and corners ground down to slide into 4 inch PVC pipe.

Mk I Crusher Diode Stack Up

The diode stack is assembled from 12 diode strips. The stack is held together by nylon weed eater line threaded thru the strips, the interleaved insulating blanks, and the nylon spacers. Representing E=ENDPLATE, S=SPACER, B=BLANK and D=DIODE, one string is assembled in order: ESBSDSBSDSBSDSBSDSBSDSBSDSE the other in the order : ESDSBSDSBSDSBSDSBSDSBSDSBSE. These two strings are laid side by side and connected like a "staircase" so that alternating between sides the potential rises monotonically from left to right. A sheet of acrylic is caged between the strings to prevent arcing. Take care to keep potential gradients uniform and avoid burrs, sharp points and anything that would cause a high gradient.

Mk I Crusher Diode Stack in Can

Although if carefully constructed the rectifier stack might survive operation in air for a short time, it is canned in clear mineral oil to prevent corona. The casing is made of 4 inch PVC; the end caps are fitted with brass toilet tank bolt sets to provide mechanical support and electrical terminals. An additional hole is drilled in the anode end for oil fill, and is tapped to accept a 1/4-20 binder head nylon screw and O-ring to seal the rectifier.

Mk I Crusher Diode Stack in Can

There is no pressure relief. Solvent welded PVC can accommodate 10% volume expansion, plenty to cover 100 W of internal dissipation expected. Although the rectifer stack is derated to 40% PIV, the most likey mode of failure is cascading reverse breakdown due to mismatched reverse leakage current or due to dielectric failure. After the first few diodes fail, the cascade will proceed quickly as the stored energy in the Theta Pinch machine will avalanch thru the stack causing an explosive failure. A pressure relief would be pitifully inadequate, so precautions are instead directed to operating the rectifiers in an area where people and property would not be injured by a violent failure of the rectifier stack.

History and Status

Mk I Crusher Construction Pictorial


Jul 2000, Bought surplus capacitors.
Jul 2001, Capacitor bank trolley built (to get capacitors off the floor).
Oct 2001, Capacitor bank complete (had to hunt 1/2-20 brass nuts and washers).
Nov 2001, Switch contacts built. Rectifiers stuck at post office. Switch redesigned and built.
Dec 2001, High Voltage rectifier stack assembled, tested.
Dec 2001, Work Cell assembled and mounted on switch. More rectifiers in work.
Dec 2001, Capacitors leaking oil. Tops drilled to top off with K-mart mineral oil.
Dec 2001, First shot on new years eve. Crusher assembled and fired at 40 Joules.
Jan 2002, Voltage doubling rectifier added, Crusher fired at 400 Joules.

bar

Altair Home

Confirm "reception" of Altairs Crusher page

crusher.html, Copyright © October 2001, Altair.

EMail altair@altair.org