March 2006
 

The world's largest capacitor bank

Designed and installed by Rheinmetall Waffe Munition

Presenting the future at the press of a button: Saxony's Prime Minister Prof. Dr. Georg Milbradt recently inaugurated the centrepiece of the new High Magnetic Field Laboratory Dresden at the Rossendorf Research Centre (FZR): the €10 million capacitor bank. Working in close collaboration with physicists and engineers from FZR, experts from Rheinmetall Waffe Munition designed and installed this pulsed, capacitive power supply system. Capable of storing 50 megajoules of energy and used to drive magnetic coils with very high and super-short energy pulses, it is the world's largest and most advanced capacitor bank.
 

The world's largest and most advanced capacitor bank is the centrepiece of the new High Magnetic Field Laboratory of the Rossendorf Research Centre. Costing around €10 million, this pulsed, capacitive power supply system was designed and installed by experts from Rheinmetall Waffe Munition in close collaboration with FZR scientists. (Photo: Jürgen Lösel, Sächsische Zeitung)

The new High Magnetic Field Laboratory in Dresden (HLD), which cost some €24.5 million to build, will produce the strongest pulsed magnetic fields ever generated, helping to supply information on the properties of solids, fluids and particles. "High magnetic fields are extremely beneficial for research in areas like high-temperature superconductors as well as for determining the characteristics of metals and semiconductors, not to mention in engineering applications such as material forming", explains Professor Joachim Wosnitza, who heads the HLD Institute at the Rossendorf Research Centre, noting that "strong magnetic fields can be used to form steel or light metals, much like high-pressure presses. Special parts for the automotive and aircraft industry can be manufactured in this way."

Ideally, the characteristics of modern semi-conductor or opto-electronic materials should be investigated in high magnetic fields and at low temperatures. This makes it possible to determine the electron density of semiconducting materials as well as its opto-electronic properties with extreme accuracy.

Spintronics is another area which the experts at the Rossendorf Research Centre will be investigating with the aid of the new High Magnetic Field Laboratory. This emergent technology, which is still in the research phase, uses the magnetic moment of the electron to display and process information, and not just the charge (as is the case with conventional semiconductor electronics); the spin of the electron produces its magnetic moment.
 

Designed by specialists from Rheinmetall Waffe Munition GmbH, the world's most advanced capacitor bank was recently commissioned at the new Dresden High Magnetic Field Laboratory. The system can drive magnetic coils with very high and super-short energy pulses. The coil winding machine manually winds the magnetic field coil, which is subsequently driven by the energy in the capacitor bank to generate high magnetic fields in the inner bore hole for various research projects. (Photo: Rossendorf Research Centre)

"Researchers expect spintronics to yield new components which will switch the electron with the spin and thus be far quicker than elements common today. Basic research being conducted today at the High Magnetic Field Laboratory Dresden will allow the microelectronics industry to manufacture new components with even faster processors or higher storage densities in future", predicts Woznita.

A capacitor bank – designed by RWM experts in close cooperation with scientists from the Rossendorf laboratory – supplies the energy (current pulses) required to produce the pulsed high magnetic fields. In order to carry out tests of this type, 50 megajoules (MJ) of electromagnetic energy and a peak current of several hundred kiloamperes (kA) are needed to generate a magnetic field of 100 Tesla (three and a half million times the earth's magnetic field).

The most advanced and efficient means of storing this energy and then pulsing it to the magnetic coil is to use a capacitor bank. To put this into perspective, the same amount of energy is released as when the driver of a diesel-powered locomotive slams on the brakes to stop a train travelling at 150 kph – and this in the unbelievably short space of time of a few hundred milliseconds seconds.

RWM project leader Jürgen Hoffmann and his team breathed an audible sigh of relief when Saxony's Prime Minister Milbradt hit the starter button of the High Magnetic Field Laboratory to put the ultramodern system into operation. After all, the 45-year-old Rheinmetall engineer and his team (consisting of up to nine experts at times) had invested a great deal of time, energy and expertise in this flagship project.
 

"The basic research being conducted at the Dresden High Magnetic Field Laboratory will allow the microelectronics industry to manufacture new components with even faster processors or higher storage densities in future," declares Prof. Joachim Wosnitza, pictured here with the magnetic coil for generating high magnetic fields. (Photo: Rossendorf Research Centre)

"Plans for using our capacitor bank as a power supply system date back to 2002; actual installation of the system at FZR began in 2004. Of course, before delivering it to the research centre, we set up all of the system components – including the input module, the capacitor module and the output module – on a scale of 1:1 at Unterlüß and tested them in every way imaginable", recounts Hoffman. As he sees it, this successful project underscores Rheinmetall's expertise in the power supply systems market: "Not only did we complete the Dresden project in the relatively short timeframe of just three years; it also demonstrates that we can supply rock-solid German engineering – a condition stipulated in the contract, by the way."

Keen to emphasize "the intensive, rewarding cooperation with scientists from Rossendorf", Hoffmann also notes that the project has attracted international recognition – further confirmation of the quality of the work performed. "We have already received a request for proposal from the research centre in Toulouse, which is interested in two similar modules." He takes this as a genuine compliment, coming from what was previously Europe's biggest high magnetic field laboratory. Researchers at the Laboratoire National des Champs Magnétiques Pulses currently use a capacitor bank with a storage capacity of only 14 megajoules.

The experience and expertise needed to build such systems is an offshoot of numerous RWM military research and technology projects for developing electrically operated cannon, lasers and microwave weapons. "Over the years, we have developed portable and stationary power supply systems in a variety of output categories, ranging from one joule units with very high repetition rates to 100 kilojoule systems, right through to the 30 megajoule system used for firing single rounds at our test centre in Unterlüß", notes Dr. Gerd Wollmann, head of direct energy weapons at RWM. The 49-year-old physicist considers the Dresden project to be a strategically important reference: "The 50 megajoule system at the Rossendorf research centre shows that it's perfectly feasible to apply certain aspects of military technology to civilian activities, producing successful niche solutions at the same time as fostering our business interests."
 

The new High Magnetic Field Laboratory Dresden at the Rossendorf research centre. (Photo: Rossendorf Research Centre)