Superconducting magnet issues "shaken" out of them, until they are eventually able to operate reliably at their full planned current without experiencing quenches. Although the idea of making electromagnets with superconducting wire was proposed by Heike Kamerlingh Onnes shortly after he discovered superconductivity in 1911, a practical superconducting electromagnet had to await the discovery of superconducting materials that could support large critical supercurrent densities in high magnetic fields. The first successful superconducting magnet was built by G.B. Yntema in 1955 using niobium wire and achieved a field of 0.7 T at 4.2 K. Then, in 1961, J.E. Kunzler, E. Buehler, F.S.L. Hsu,
Heike Hennig 1995, Heike Hennig came back to Germany. From 1998 onwards, she worked as a freelance choreographer and teacher. She instructed body- and moving-oriented teaching-methods at the "Palucca School of Dance", the "University of Leipzig" and the "Academy of Visual Arts in Leipzig" as well as in interdisciplinary workshops including anatomy, painting and choreography. In 2000, Heike Hennig founded the FZTM (Forum of Contemporary Dance and Music) in Leipzig, together with Friedrich U. Minkus, and her ensemble Heike Hennig & Co. As director she developed numerous stage pieces and interdisciplinary art projects at many different stages and art institutions in Leipzig,