The strongest fields encountered from permanent magnets on Earth are from Halbach spheres and can be over 4.5 T. The record for the highest sustained pulsed magnetic field has been produced by scientists at the Los Alamos National Laboratory campus of the National High Magnetic Field Laboratory, the world's first 100-tesla non-destructive magnetic field. In September 2018, researchers at the University of Tokyo generated a field of 1200 T which lasted in the order of 100 microseconds using the electromagnetic flux-compression technique.
A particle, carrying a charge of one coulomb, and moving perpendicularly through a magnetic field of one tesla, at a speed of one metre per second, experiences a force with magnitude one newton, according to the Lorentz force law. As an SI derived unit, the tesla can also be expressed as
In the production of the Lorentz force, the difference between electric fields and magnetic fields is that a force from a magnetic field on a charged particle is generally due to the charged particle's movement, while the force imparted by an electric field on a charged particle is not due to the charged particle's movement. This may be appreciated by looking at the units for each. The unit of electric field in the MKS system of units is newtons per coulomb, N/C, while the magnetic field (in teslas) can be written as N/(C⋅m/s). The dividing factor between the two types of field is metres per second (m/s), which is velocity. This relationship immediately highlights the fact that whether a static electromagnetic field is seen as purely magnetic, or purely electric, or some combination of these, is dependent upon one's reference frame (that is, one's velocity relative to the field).
10,000 (or 104) G (Gauss), used in the CGS system. Thus, 10 kG = 1 T (tesla), and 1 G = 10−4 T = 100 μT (microtesla).
1,000,000,000 (or 109) γ (gamma), used in geophysics. Thus, 1 γ = 1 nT (nanotesla).
42.6 MHz of the 1H nucleus frequency, in NMR. Thus, the magnetic field associated with NMR at 1 GHz is 23.5 T.
One tesla is equal to 1 V⋅s/m2. This can be shown by starting with the speed of light in vacuum,c = (ε0μ0)−1/2, and inserting the SI values and units for c (2.998×108 m/s), the vacuum permittivityε0 (8.85×10−12 A⋅s/(V⋅m)), and the vacuum permeabilityμ0 (12.566×10−7 T⋅m/A). Cancellation of numbers and units then produces this relation.
35.4 T – the current (2009) world record for a superconducting electromagnet in a background magnetic field
45 T – the current (2015) world record for continuous field magnets
100 T – approximate magnetic field strength of a typical white dwarf star
108 – 1011 T (100 MT – 100 GT) – magnetic strength range of magnetar neutron stars
Notes and references
^"Details of SI units". sizes.com. 2011-07-01. Retrieved 2011-10-04.
^"Strongest non-destructive magnetic field: world record set at 100-tesla level". Los Alamos National Laboratory. Retrieved 6 November 2014.
^D. Nakamura, A. Ikeda, H. Sawabe, Y. H. Matsuda, and S. Takeyama (2018), Magnetic field milestone
^The International System of Units (SI), 8th edition, BIPM, eds. (2006), ISBN 92-822-2213-6, Table 3. Coherent derived units in the SI with special names and symbols Archived 2007-06-18 at the Wayback Machine
^Gregory, Frederick (2003). History of Science 1700 to Present. The Teaching Company.
^Parker, Eugene (2007). Conversations on electric and magnetic fields in the cosmos. Princeton University press. p. 65. ISBN 978-0691128412.
^Kurt, Oughstun (2006). Electromagnetic and optical pulse propagation. Springer. p. 81. ISBN 9780387345994.
^Herman, Stephen (2003). Delmar's standard textbook of electricity. Delmar Publishers. p. 97. ISBN 978-1401825652.
^McGraw Hill Encyclopaedia of Physics (2nd Edition), C.B. Parker, 1994, ISBN 0-07-051400-3
^"Geomagnetism Frequently Asked Questions". National Geophysical Data Center. Retrieved 21 October 2013.
^Panofsky, W. K. H.; Phillips, M. (1962). Classical Electricity and Magnetism. Addison-Wesley. p. 182. ISBN 978-0-201-05702-7.
^"Ultra-High Field". Bruker BioSpin. Retrieved 2011-10-04.
^"Superconducting Magnet in CMS". Retrieved 9 February 2013.
^"The Strongest Permanent Dipole Magnet" (PDF). Retrieved 2 May 2020.
^"ITER – the way to new energy". Retrieved 2012-04-19.
^Hesla, Leah. "Fermilab achieves 14.5-tesla field for accelerator magnet, setting new world record". Retrieved 2020-07-13.
^"Of Flying Frogs and Levitrons" by M. V. Berry and A. K. Geim, European Journal of Physics, v. 18, 1997, p. 307–13" (PDF). Archived from the original (PDF) on 8 October 2020. Retrieved 4 October 2020.
^"The 2000 Ig Nobel Prize Winners". Retrieved 12 May 2013.)
^"Superconductor Traps The Strongest Magnetic Field Yet". Retrieved 2 July 2014.
^ ab"Mag Lab World Records". Media Center. National High Magnetic Field Laboratory, USA. 2008. Retrieved 2015-10-24.