M&W Current Leads offers customers a range of well-proven superconducting current lead designs – including vapor cooled current leads (VCCL) and conduction cooled configurations – optimised for current capacity:
We offer our customers access to 20+ years of experience and a network of specialists and likeminded people. You can learn more about Mark & Wedell, our history and how we operate as a business here: About M&W.
M&W Current Leads takes full ownership of the entire process starting with concept, design, engineering, production, FAT and thorough documentation.
A project can be the development as a prototype, a small series, or a high-volume production.
Our commitment is always the same:
In addition to unparalleled quality, you get optimised current leads that will serve your installation well and be in operation for years to come.
The Big Science market consists of large research facilities, scientific test centres and is often funded by governments or groups of governments. In many scientific fields, major progress is only achieved through Big Science facilities, which are needed to perform exotic experiments.
The unique mechanical and electrical engineering competences and high level of craftsmanship of M&W Current Leads enable us to offer products and solutions to the demanding customer base, where quality, durability and precision is key.
The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator and the largest scientific test instrument ever built. The collider is a 27 km long circular accelerator placed 100 m underground. The particles are accelerated in 2 independent vacuum tubes, with one beam traveling clock-wise and one beam traveling counter clock-wise.
The particle accelerators accelerate protons and other particles to near the speed of light, before smashing them together at so-called collision points. This is done in order to study the fundamental interactions of nature. The LHC was built to test the Standard Model of particle physics: a classification of all known elementary particles – the building blocks of the world around us. In 2012 the LHC confirmed the detection of the Higgs Boson, which was predicted in 1964. Mark & Wedell has so far developed and supplied CERN with more than 450 superconducting current leads units.
This principal sketch illustrates an M&W current lead type CvHH – a vapor cooled current lead (VCCL) suitable for currents above 10,000 A. In this design, boil-off gas cools the copper section from room temperature down to the HTS transition temperature, significantly reducing heat leak to the cryogenic system. The current enters the warm terminal and exits at the cold terminal, passing through sections where different materials and coolants are optimised for thermal performance.
Current leads are a key component in any superconductor technology. It leads the current from the ambient temperature of 20 ⁰C to the cold environment where the superconducting wires are operated. The superconductor must be cooled to cryogenic temperatures, which for low temperature superconductors is around 4 K (-269 ⁰C). At this temperature, the superconductor enters its superconducting state and has no electrical resistance.
Particle accelerators use strong magnetic fields either to bend or to focus/de-focus the particle beams. To create such a strong magnetic field, strong superconducting electromagnets are required. These magnets rely on thin superconducting wires that can carry huge electrical currents, thanks to zero resistance, and can thus create very strong magnetic fields, in the range 1-10 T. Thousands of amps are entering the current leads through the warm terminal that consists of a massive copper block and exits through the cold terminal in a tiny superconducting wire.
In the following you will see how this transition between the large copper conductor at the warm terminal and the small superconductor at the cold terminal looks like.
When an electrical current passes through for instance a copper wire, the wire will heat up. This is due to thermal losses in the wire coming from the electrical resistance in the copper. If the wire surroundings cannot keep the material below a certain temperature, the wire will overheat and eventually melt-down. Therefore there is a limit to how much current any given copper wire can lead. The image on the left shows copper wires connected to the warm end of a current leads, and the copper wires are capable of carrying 15.000 A.
A thicker copper wire can of course carry more current, but the thousands of amps required to create the strong magnetic field required in particle accelerators, would make the copper cable too thick and impractical, and at the same time generate a lot of thermal losses.
Some materials lose their electrical resistance at low temperatures. These materials are called superconductors and they do not have any ohmic losses when an electrical current is passing through them. This makes superconductors ideal as conductors in electromagnets where huge magnetic fields shall be achieved. The image on the left shows Niobium-Titanium wires, also capable of carrying 15.000 A. The current density in these wires is 4-500 times larger than the current density of similar copper wires.
Superconducting materials become superconducting below a certain transition temperature, also called critical temperature Tc, whereas non-superconducting materials still have a finite resistance, even at 0 K (-273 ⁰C). The resistance of these two types of materials is shown in the following figure, where the resistance as a function of temperature is illustrated.
The superconducting state of the material also depends on the applied magnetic field and the current, but in most applications, the superconductor supports a current density which is hundreds of times larger than that of copper wires.
Scientists keep discovering new types of superconductors, and superconductors with a high transition temperature are highly sought-after. Some of the recent discoveries include superconductors with transition temperatures at almost room temperature, but only under extreme conditions, such as a pressure of 155 GPa! [Click to enhance graph]
Current leads come in many shapes and forms depending on the specification and applications. There are many considerations to take into account when designing a current lead.
The typical operating current is from a few hundred to tens of thousands of amps. The current density changes dramatically through the current leads. For a 12 kA CL, for instance:
Thus the current density is increased with a factor of about 400.
The coolant consumption depends very much on the application and the operational conditions.
November 12, 2025
Mark & Wedell has announced it has secured a significant contract to engineer and deliver state-of-the-art superconducting solutions for a key European fusion energy research project.
September 10, 2025
Through a strategic partnership, Mark & Wedell will integrate Faraday Factory Japan‘s cutting-edge REBCO 2G HTS tape into our superconducting current leads, powering the future of fusion energy.
July 30, 2025
Mark & Wedell (M&W) and SuperNode are proud to announce that M&W’s custom-engineered highcurrent leads have played a key role in SuperNode’s historic demonstration of a superconducting power cable using a polymeric cryostat—the first of its kind globally.