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,
Frans Michel Penning of Gorinchem on 12 September 1894. Penning attended the University of Leiden. He studied mathematics and physics as a graduate student under Heike Kamerlingh Onnes. Penning's doctoral work involved measuring thermodynamic properties of various gases at extremely low temperatures. Penning received his PhD on June 25, 1923 with a dissertation entitled 'Metingen over isopyknen van gassen bij lage temperaturen' (Measurements on Isometric Density Lines of Gases at Low Temperatures). His father Louwrens Penning, was a popular novelist in the Dutch literary community; most known for romanticizing the Anglo-Boer War. His mother was Adriana Jenneke Machelina Heijmans. Penning married to Margje