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,
Jacob Clay year later. In 1936 he became a full member. Clay died on 31 December 1955 in De Bilt Jacob Clay Jacob Clay () (1882–1955) was a prominent Dutch physicist who first suggested and provided evidence that cosmic rays are charged particles. Clay was born "Jacob Claij" in Berkhout on 18 January 1882 as the son of Pieter Claij and Neeltje Molenaar. After attending the Erasmiaans Gymnasium, he studied physics at the University of Leiden under Heike Kamerlingh Onnes and Hendrik Antoon Lorentz. After obtaining his Ph.D. degree in 1908 he married Tettje Clay-Jolles with whom he had a son. After