Niobium is a soft, grey, ductile transition metal with atomic number 41. A majority of niobium is currently mined in Brazil, and its primary commercial use is as an alloy to improve strength, heat resistance and ductility in steel. Niobium is also one of a few elements that will superconduct below a critical temperature. The resistivity of niobium drops to zero below its critical temperature of 9.26 K (-443 °F). Niowave takes advantage of niobium’s superconducting properties to fabricate our highly efficient superconducting accelerators. High purity niobium has a value roughly equal to silver on a per pound basis. Niowave has invested significantly to build up the largest high-purity niobium stockpile in North America.
Niowave has over ten years of experience in custom fabrication of normal conducting and superconducting radio frequency cavities. We have built cavities for Brookhaven National Lab, Jefferson Lab, Los Alamos National Lab, Fermilab, CERN and others. Cavities range in frequency from 28 MHz up to 9 GHz. Niowave has experience building cavities of various shapes as well, including: elliptical cell, spoke, half wave, quarter wave, and crabbing cavities. With our stock of niobium, we are able to provide quick turnaround in fabrication by cutting out delays of material acquisition.
In superconducting accelerators, focusing of high-energy beams can be achieved by incorporating superconducting magnets into the module design. Especially for superconducting electron guns, a strong magnet near the exit of the gun is important to preserve the quality of the beam. Niowave builds superconducting magnets for accelerators, with in-house expertise in magnet design, winding of superconducting coils, and testing of the magnet assemblies before delivery.
The residual resistivity ratio (RRR) measurement is an important measurement of the purity of Niobium. The higher the RRR value, the higher the purity of the material. Higher purity niobium is desirable for fabrication of superconducting accelerators. Niowave provides testing of niobium to determine the RRR value of bulk niobium. This testing only requires a small sample 2 mm x 2 mm x 76 mm. Niowave has the capability to machine these samples from bulk material, and test them at our facility. Niowave is the only company in North America to offer this service, and can report results within four weeks of receipt of samples.
Niobium is superconducting at temperatures below 9.26 K. For this reason, Niowave uses liquid helium at 4.2 K to keep accelerators superconducting. This is done by different means for different accelerators. For a one off test, we use dewars of liquid helium, and simply boil off the liquid over the course of the test. For long term operation, this would become financially prohibitive, so we have helium refrigerators to keep systems cold over the course of a long term operation. Niowave has three different (four total) helium refrigerators available for accelerator operation.