Monthly Archives: September 2014

Setup and Operation

To begin the project, proceed as follows:

1. Assemble the warping and blocking coils, as shown in Figure 7-2.

2. Position the warping coil assembly at the desired location and connect it up as shown.

Four turns of #t2 vinyl wire close wound and taped

Aluminum can

Trigger pulse blocking coil is made from several turns of the discharge wire wound onto a high – permeability, low-level, saturating ferrite core or loroid. This scheme provides a high impedance to the trigger pulse but is transparent to the main discharge current pulse.

Attempt to keep discharge leads as short and direct as possible lo minimize stray inductance.

Safety discharge probe

RED LEAD

Setup and Operation

Setup and Operation

Figure 7-2 Setup for magnetic can crusher

Note the inclusion of the trigger pulse block­ing inductor in one of the coil leads. This part provides reliable triggering when using low- impedance loads.

You may make a suitable stand that will auto­matically position the pop can. Note that the coil is at a ground potential and poses a mini­mal shock threat when used as directed. It can be safely set up for public demonstration. Contact the factory for suggestions.

3. Set the controls as follows (reference front panel drawing, see Figure 3-7):

Voltage Control Switch (R8/S2) should be set to FCCW (OFF).

High-Voltage Power Switch (S4) should be set to OWN (OFF).

Charging Switch (SI} must be pressed to acti­vate the charging action.

4 Plug into 115 volts-alternating current (VAC) and turn on the voltage control to verify both light-emitting diode (LED) lamps coming on:

The red lamp (LAI) indicates the system is in

an “on” state.”

The green or yellow lamp (LA2) comes on but extinguishes in the charge cycle and comes on when the preset voltage level is reached, indi­cating the system is ready to “fire.’"

5. Turn the voltage control off and unplug it once the previous steps are verified.

6. Set the charge voltage control to the 3,000- volt setting as marked on the panel. Plug the unit into 115 VAC and turn on the high-volt­age safety switch S4.

7. Depress the *charge switch (SI) (the green or yellow lamp now goes off) and note the increasing voltage on the panel voltmeter reading, indicating the energy storage capaci­tors are charging. Allow it to charge to the preset voltage as in step 6. Note the LA2 lamp now turns on when the set level is reached, indicating that the system is ready to fire.

8. Depress the fire switch and note a loud report of discharge in the spark switch. You should see some deformation around the can under the coil. Repeat at 4,000 volts and the can deforms to about 50 percent of its original shape.

over the 4 kilovolts (Kv) setting except for experi­menting. The system may be test-fired up to 5,000 volts for experimental research but may require the continual maintenance of spark switch electrodes. Always increase in 500-volt increments to verify sys­tem integrity.

It may be a good idea to check the front panel meter calibration from time to time. Use an exter­nally calibrated meter connected across the energy storage capacitors to verify the panel voltage settings.

The spark gap is factory set at.1 inches for opera­tion at 3 to 4 Kv. Lower-voltage operation may require decreasing the gap for reliable triggering. Operations over 4 Kv will require widening to pre­vent premature triggering. You may have to tweak the gap by loosening one of the Allen set screws for your particular range of operation.

You should place a high-permeability ferrite core wound with two to three turns on one of the leads from the crushing coil to the G2.This part will increase the inductance of this lead to block the trig­ger pulse from being shorted by the low impedance of this coil yet quickly saturate at the main discharge current.

It is important that the all connection leads from the capacitor bank the pulser and the crusher coil be as short as possible to reduce lead inductance for optimum results.

The spark switch may prematurely fire if dirty or improperly gapped.

Special Notes

System energy varies as the square of the increased voltage. For example, energy will increase by 9 when the voltage is increased from 1.000 to 3,000. You may

Special Notes

Special Notes

STRIP

SAFETY DISCHARGE PROBE— Use rigid piece of 16-24* plastic – tube AND

with clearance ID for #12-14 stranded wire. TIN

Figure Б-3 Setup of wire explosion project

go to 4,500 volts for an increased effect, add more capacity, or both. Use caution.

Also note that the continued operation at over

4. volts eventually will erode the spark switch. Do not go over the 4 Kv setting except for experiment­ing. The system may be test-fired up to 5,000 volts for experimental research but may require continual maintenance of spark switch electrodes. Always

increase in 500-volt increments to verify system integrity.

It may be a good idea to check the front panel meter calibration from time to time. Use an exter­nally calibrated meter connected across the storage capacitors to verify panel voltage settings.

The spark gap is factory set at.1 inches for opera­tion at 3 to 4 Kv. Lower-voltage operations may

require decreasing the gap for reliable triggering. Operation over 4 Kv will require widening to prevent premature triggering. You may have to tweak the gap by loosening one of the Allen set screws for your par­ticular range of operation.

You should place a high-perineability ferrite core wound with two to three turns on one of the leads from the chamber to the G2.This part will increase the inductance of this lead to block the trigger pulse from being shorted by the low impedance of the wire yet quickly saturate at the main discharge current.

It is important that all connection leads from the capacitor bank to lhe pulser and the chamber be as short as possible to reduce lead inductance for opti­mum results.

The spark switch may prematurely fire if dirty or improperly gapped.

Danger! Always unplug and discharge energy – storage capacitors using the safety discharge probe before making any adjustments.

Place a piece of white paper adjacent to the wire and observe the interesting pattern left once it explodes.

Special Notes

Special Notes

Figure 7-1 A magnetically crushed can

This project is an excellent demonstration of pulsed magnetics where a normal, everyday aluminum soda can is crushed into an hourglass configuration (see Figure 7-1). Several of these systems are on interac­tive display at public museums where it has been reported that students would bring their own cans, placing them into the lest coil and keeping them as souvenirs.

Construction requires a working high-energy pulser as described in Chapter 3, “High-Energy Pulser,” along with the assembly of the shaping coil.

It is shown using energy-storage capacitors currently available on the surplus market. These values can be altered within limits to allow the use of available capacitors that the builder may have on hand. The project requires experience in the handling of high – voltage, high-energy devices. This can also be an excellent museum demonstration when performed by a qualified adult.

Theory of Operation

An energy-storage capacitor is charged from a pro­grammable, controlled current source 10 a selected high voltage. Тії is capacitor is now switched by a trig­gered spark gap, discharging all the stored energy into and vaporizing a wire. A shock wave is produced by the rapid oxidization of the object. This project is suitable for a science class demonstration ol the con­cept if properly supervised with qualified personnel.

Setup and Operation

To begin the project, follow these steps:

1. Assemble the explosion chamber, as shown in Figure 6-2.

2. Position the explosion chamber and connect it up as shown in Figure 6-3. The transparent shield section provides protection ю ihe oper­ator but is open in the rear and side sections. The rear section is used to place the target material where the explosive blast exits. It is suggested to completely shield the chamber if spectators are to be in the area.

Note the inclusion of the trigger pulse block­ing inductor in one of the leads. This pan

Theory of Operation

Figure Б-I Explosion chamber

provides reliable triggering when using low – impedance loads such as wires and so on.

3. Note the controls as shown in Figure 3-7 of Chapter 3.

Voltage Control Switch (R8/S2) should be set to FCCW (OFF).

High-Voltage Power Switch (S4) should be set to DOWN (OFF).

Charging Switch (SI) must be pressed to acti­vate the charging action.

4. Connect a 3- to 4-inch piece of #24 bare cop­per wire to the terminal block as shown. Make sure that the wire is firmly clamped by giving it a tug. Place a safety cover over the assembly if required.

5. Plug into 115 volts-alternating current (VAC) and turn on voltage control to verify both light-emitting diode (LED) lamps coming on:

The red lamp (LAI) indicates the system іь in an “on” state.

The green or yellow lamp (LA2) comes on but extinguishes in the charge cycle and comes on when the preset voltage level is reached, indi­cating the system is ready to “fire.”

Turn the voltage control off and unplug it once the previous steps are verified.

6. Set the charge voltage control to a 3,000-volt setting, as marked on the panel. Plug unit into 115 VAC and turn voltage control.

7. Depress ^charge switch SI (the green or yel­low lamp now goes off) and note the increas­ing voltage on the panel voltmeter reading, indicating the energy storage capacitors are charging. Allow charging to the preset voltage as in step 6. Note that the LA2 lamp now turns on when the set level is reached, indicat­ing that the system is ready to fire.

Theory of Operation

Introducing all new BLAST ARTtm

Place a piece of white paper near the target wire and note the myriad of blast patterns produced. You may experiment by placing paper at different locations and distances relative to the wire, noting the various effects of the blast. This is an excellent form of a new art that we are introducing called BLAST ART where an infinite amount of weird and bizarre blast patterns are permanently embedded onto many surface materials Wires of different sizes and materials may be experimented with further, adding to the effects possible.

Figure 6-2 Explosion chamber scheme

8. Depress the fire switch and note a loud report of discharge in the spark switch. The wire should vaporize with a bright flash and a loud report similar to a firecracker. Repeat at 4,000 volts, noting a brighter flash and a louder bang.

Special Notes

The system as shown was tested with two 32 micro­farad (mfd), 4 kilovolt (Kv) capacitors in parallel for a total energy of 500+ joules. The projectile velocity was more than 200 meters per second (m/s). It is sug­gested to use only one capacitor for the science proj­ect approach.

Serious experimenters should consider our HEP90 higher-energy charger and additional energy-storage capacitors. The gun section must be beefed up for any significant increase in energy. Some suggestions are the following if stored energy is to exceed 1,000 joules:

• The entire assembly must be placed inside an explosion shield consisting of a half-inch of

Lexan.

• Retaining washers should be replaced with multiple washers or a sleeve all securely sol­dered in place.

• The breech tube must be sleeved into a sec­ondary sleeve of equal wall thickness. The entire breech assembly is now inserted into a steel tube or pipe for further reinforcement.

• The mounting blocks should be reinforced with a V4-inch angle of aluminum or steel.

• The mounting base should be fabricated from aluminum or steel.

Cut out on dashed lines

Special Notes

BARREL BLOCK FAB

BREECH PLUG BLOCK FAB

Views showing gun components in place

Materials

t X 3/4 X t-t/4" PVC BLOCK 1/2X2” SPRING COPPER

Special Notes

Figure 5-6 Plasma gun top view showing muzzle blast when firing

Figure 5-5 Mounting scheme showing mounting blocks

Note spring copper electrodes are also used to solder input feed wire

Special Notes

Djpsss

ш RTR1I

Special Notes

Attempt to keep all discharge wire as short as possible to avoid inductance.

Figure 5-7 Setup of plasma thermal gun

When attempting to fire larger systems, it is impor­tant to increase the energy in small steps, always rechecking the system integrity for any damage resulting from prior shots. You will need the follow­ing parts to make this system:

• The fabricated parts as shown in Figures 5-4 and 5-3. These can be purchased through the factory but will require final fitting. Raw materials are available through most hard­ware stores.

• The energy storage caps are shown as 32 mfd/4500 volts and are available through the factory. Other values obtainable through sur­plus sources may be used, but we cannot guar­antee performance.

• The HEP3 charger/pulser/spark switch is available through the factory as a kit or as an assembled unit. Our HEP9 higher-powered version intended for more serious experimen­tal research is also available. It can charge banks of multiple capacitors up to 5,000 joules.

Danger! If a system uses a push-on/oft charging switch, it will automatically recharge the capacitor bank after firing. Basic units use a push-on switch lor the charging switch, as charging always requires the switch to be depressed, providing safer opera­tion at the cost of convenience. The red lamp (LAI) indicates the system is in an “on” state. The green or yellow lamp (LA2) comes on but extinguishes in the charge cycle and comes on when the preset voltage level is reached, indicating the system is ready to “fire.”

Special Notes

The explosion of wires or objects by the rapid dis­charge of high electrical currents produces some interesting phenomena. The obvious audible and visual display is not the only objective, and it does find use as a part of special effects and demonstra­tions. The detonation of a wire from a moderate energy source can provide a blast equal to a pyrotechnic high explosive. The detonation velocity can exceed thousands of meters per second, produc­ing high-speed microparticlcs and switching high cur­rents in the multigigawatts at nanosecond speeds for electromagnetic pulse (EMP) generation and electro­kinetics. The project may be scaled up for serious research with an obvious increase in high voltage handling and ballistic hazards. This project requires experience in the handling of high-voltage, high – energy deviccs.

Construction requires a working higlr-encrgy pulser as describetl in Chapter 3. “High-Energy Pulser," along with the assembly of the explosion chamber. It is shown in Figure 6-1 using energy – siorage capacitors currently available on the surplus market. These values may be altered within limits in order to use available capacitors that the builder may have on hand. It can be hazardous and requires pro­tective eyewear. This project can function as an excel­lent museum demonstiation when performed by qualified adult personnel. Safety eyewear must be worn by the operator.

Theory of Operation

An energy-storage capacitor is charged from a pro­grammable, controlled current source to a selected high voltage. This capacitor is switched by a triggered spark gap, dumping all the stored energy into a small- volume explosion chamber and vaporizing a thin, alu­minum wire placed inside the chamber. A pressure wave forces a projectile out the barrel to a high velocity. This project is suitable for a science class demonstration if properly supervised with qualified personnel.

Rssembly Steps of the Thermal Gun

To construct the thermal gun, follow these steps:

1. Fabricate the barrel and breech plug, as shown in Figure 5-2. rounding off all edges and inner barrel ridges.

2. Fabricate the brcech tube, as shown in Figure 5-3. Note that the mating of the barrel and breech plug are precision-drilled using frac­tional bits. The inner diameter should be.007 to.008 over the outer dimensions of the barrel

Theory of Operation

Lengtn may vary from 2 to 8 inches

Material isJ^-incTi brass tubing, and approximate OD is 4 inch

Material is %-inch brass dowel

Round off edges and clean with steel wool –

Figure 5-2 Barrel and breech plug fabrication

and breech plug to allow for clearance of the exploding wire, as shown in Figure 5-4.

If the clearance is too tight, it will be difficult to insert the barrel and breech plug without breaking the wire.

If the clearance is too loose, improper contact will occur on the exploding wire. Drill a bit at a time to establish the proper fitting action.

3. Solder the brass retaining washers at certain points, as shown, to allow the proper gauging of the barrel and breech plug insertion depths into the breech tube.

4. Fabricate projectiles from ‘/2-inch pieces of 74- inch plastic, polycarbonate, or wooden dowels. Round off the end to give it a bullet-like shape, creating a streamlined effect. The final assembled gun should look like Figure 5-4 and easily fit together for the reloading of the exploding wire and projectile. You will note the metal barrel and breech plug are also the feed electrodes connected to the exploding wire via a sandwiching action. The high-pow – ered current pulse is now applied to these elcctrodes, generating an explosive, heated plasma vapor that produces a pressure wave, which forces the projectile out of the barrel.

5. Create a lab proto unit shown in Figures 5-5 and 5-6. It allows easy disassembly and pro­vides positive electrical contact to the gun electrode ends. You may have your own ideas to this approach, but the objective must be the same: good electrical contact, easy disassem­bly, and reloading.

For a smaller-diameter breech plug, use the following substeps in fabricating:

a. Precisely locate the holes and center punch.

b. Drill a ‘/y-inch pilot hole using a drill press.

c. Expand the holes to the final radius using successively larger drills.

d. Drill а ‘/іб-іпсЬ hole for a spring electrode sheet metal screw.

Theory of Operation

1 Cut off a 9“ section and parallel face ends.

2 Clamp in drill or lathe and drill a 25" through hole.

3 Drill a 4" hole to a depth of 1" from the muzzle end

4 Nole to precision drill for additional clearance of exploding wire Added clearance is equal to wire diameter.

Assemble parts with wire to verily proper fitting as shown

Figure 5-3 Breech tube fabrication

e. Drill two ‘/i6-inch holes for mounting blocks to the base section.

f. Use a band saw to cul out sections shown by dashed lines. File for final sizing and finishing.

6. Fabricate and shape the spring electrodes as shown. Use pliers and a small vise to bend them properly. These pieces must snap into the gun assembly and provide a positive contact.

7. Fabricate the base section in Figure 5-6 from a piece of V4-inch finished plywood. Sand and varnish it for a good appcarance. Mount the components as shown and clamp the wires in place using nylon clamps and ‘/2-inch sheet metal screws. Solder the leads of the feed wires to spring electrodes.

8. Connect up as shown in Figure 5-7. Use at least #16 wire. The leads must be short and direct.

9. Obtain a suitable target, such as a small pil­low. This will prevent the projectile from rico­cheting all over the place, making it hard to find for reloading.

Prep the gun with exploding wire, as shown in Figure 5*4. Snap it into the holders and insert the projectile to point as shown.

[t is assumed that the high-energy pulser is properly operating and connected as per the instructions and has a calibrated voltmeter and set spark switch. Familiarize yourself with the pulser operation.

11. Connect the high-energy pulser and energy- storage capacitors as shown. Note that the inductor L2 is not used in this project.

12. Allow charging up to 2,000 volts and then test the fire unit. Note the loud crack as the pro­jectile exits the barrel. Increase the voltage in steps of 500 and note the increase in velocity. Experiment using different projectiles, targets, and so on.

Theory of Operation

Theory of Operation

1" OD G10

Figure 5-4 Breech and gun assembly

Danger! Verify that the energy-storage capacitors are fully discharged before touching any part of the gun assembly. Always short out the capacitor termi­nals using the safety discharge probe until you are ready to operate as this eliminates any residual stored energy from accumulating.