2015 April Railgun test report

Page:1

2015 April, Railgun test report 7-04-2015

Test Report

2015 April Railgun test report Javier Luis López. Pulsotron S.L.

Contents  1

Abstract........................................................................................................................... 2

2

Fields of applications ...................................................................................................... 2

3

Some calculations for a two or more stages railgun...................................................... 2

4

Precedent ....................................................................................................................... 3

5

The rail wearing reduction systems ............................................................................... 3

6

Test results ..................................................................................................................... 4

7

Conclusion ...................................................................................................................... 6

Page:2

2015 April, Railgun test report 7-04-2015

1

Abstract 

In the April 2015 test campaign a first stage railgun was tested in different configurations The test objectives were to test reduction wearing systems and increase the efficiency over 5%

2

Fields of applications 

The railgun can be used in the following fields: - Nuclear fusion, where it must be used to accelerate targets to more than 200km/s - Space uses: to throw micro satellites and payload directly to space without using rocket engines, so payloads over 10km/s must be sent. - Military uses: anti aircraft, ground and naval objectives. The main advantages are: it can be used as a barrier against incoming missiles, destroy more targets in less time and at less cost than using missiles.

3

Some calculations for a two or more stages railgun 

The current injected in the railgun can be obtained from the following equation:

I0 =

2E0 L1

2

Where Eo is the initial energy stored at the capacity bank and L1 is the inductance of the power lines and the railgun. Then the current discharged in the railgun follows the following equation: I=I0*cos(w1*t) where

Page:3

2015 April, Railgun test report 7-04-2015

1

w1 =

L1 * C

Unfortunately L1 is increased when the bullet goes through the railgun. Then when the bullet came in a second stage of the railgun the discharged energy follows the equation: I=I1*cos(w2*t) where

I1 =

2 E1 L2

2

Where E1=E0 minus the energy wasted in the air, heating the rails and the bullet energy. It must be calculated L2 that the result current I1 must be about the same than I0 It is also recommended to use a high power diode that passes the energy from the first stage to the second in order to use the energy stored in L1

4

Precedent 

Within the Pulsotron project railgun intended for nuclear fusion uses were developed 83 railguns and 144 shots was made with them. A railgun simulator was also designed that was used in the working railguns. According to the simulations railguns can be built that throw the darts in the 10-20 km/s range.

5

The rail wearing reduction systems 

A wearing reduction system consists of high power switches and filtering that reduce the duty cycle to inject a constant current entering in the railgun along the rail. This system allows the bullet speed to be controlled and to shut down the system if the bullet gets stuck in the railgun due to a failure. It also allows to adapt to different bullet weights. Another wearing reduction is to use a delay line to smooth and spread the energy injected along the track. Yet another one is the use of protection layer covering the tracks.

Page:4

2015 April, Railgun test report 7-04-2015

As a result the track wearing was reduced so much that we had to reduce track size to thin layers to measure the wearing at more than 3kJ/mm discharges as can be seen in the following photo obtained last year:

New thin tracks

Wearing at old tracks after 20 shots at 0.6-2 kilojoules/mm The low wearing allows the railgun to be operative at full power after hundreds of shots, increase the shooting rate and accuracy and keep the tracks clean after every shot.

6

Test results 

It was made 6 shots, the best of all was the shot number 467, where the bullet reached 524 m/s (it was tested only the first stage). The energy efficiency was 38.33% as long as energy was wasted in light emission as can be seen in the following video capture:

Page:5

2015 April, Railgun test report 7-04-2015

Peak energy was injected during 116 microseconds:

In the next test a delay line was installed in order to smooth the discharged energy up to 2.4 milliseconds, as a result less light emission was generated:

Page:6

2015 April, Railgun test report 7-04-2015

Here are the high speed video captures of the bullet at the railgun exit:

Another wearing reduction system by using a rail protection layer that reduced rail erosion was also tested but it was burnt and generated too much waste that had to be removed.

7

Conclusion 

The delay line is an easy system to control the current rate injected in the rail. Efficiencies 38% were reached, but there is a way to improve this figure in the following tests. The protection layer must be improved to use one that does not generate residues The signals generated by the sensors were too weak so it is recommended to increase the diode light by using high efficiency diodes or lasers instead