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 Erkers of employers performing salary surveys (lönekartläggning) on a regular basis. Another issue is child poverty. She is also a member of the Executive Committee of the European Federation of Public Service Unions (EPSU) Heike Erkers Heike Erkers is the Chair of the Swedish labour union Akademikerförbundet SSR (in English 'The Union for Professionals'). She is currently off duty from her regular employment as a head of department at the Swedish Public Employment Service (in Swedish 'Arbetsförmedlingen'). Heike Erkers started being in enganged in labour union issues in the 1990s. In 2003 she was elected member of the board of Akademikerförbundet