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,
Tettje Clay-Jolles 1903 when she transferred to the University of Leiden. She was one of the few women who studied physics at the university. There she began her doctoral research on low-temperature physics under Heike Kamerlingh Onnes. She worked on her thesis until December 1908 when she left her studies to devote herself to her family. Clay-Jolles met and fell in love with Jacob Clay, another of Kamerlingh Onnes's students, and in 1908 the two were married. Later that year she left school to focus on her family. She spent the next twelve years raising the couple's three children. In 1920 the