Content deleted Content added
→History: Add paragraph on travelling wave electron accelerators. |
→History: add paragraph on RFQs |
||
Line 22:
In 1947, at about the same time that Alvarez was developing his linac concept for protons, [[W. W. Hansen|William Hansen]] constructed the first travelling-wave electron accelerator at Stanford University.<ref>{{cite journal |author-last=Ginzton |author-first=Edward L. |date= April 1983| title=Early Accelerator Work at Stanford |journal= SLAC Beam Line | pages=2-16 |url=http://atlas.physics.arizona.edu/~shupe/Physics_Courses/Phys_586_S2015_S2016_S2017/Readings_MS/SLAC_Early_History.pdf
}}</ref> Electrons are sufficiently lighter than protons that they achieve speeds close to the [[speed of light]] early in the acceleration process. As a result, "accelerating" electrons increase in energy, but can be treated as having a constant velocity from an accelerator design standpoint. This allowed Hansen to use an accelerating structure consisting of a horizontal [[waveguide]] loaded by a series of discs. The 1947 accelerator had an energy of 6 MeV. Over time, electron acceleration at the [[SLAC National Accelerator Laboratory]] would extend to a size of {{convert|2|mi|km}} and an output energy of 50 GeV.<ref>{{cite book |last1=Neal |first1=R. B. |title=The Stanford Two-Mile Accelerator |chapter=Chap. 5 |publisher=W.A. Benjamin, Inc |year=1968 |___location=New York, New York |page=59 |chapter-url=http://www.slac.stanford.edu/spires/hep/HEPPDF/twomile/Chapters_4_5.pdf |access-date=2010-09-17}}</ref>
As linear accelerators were developed with higher beam currents, using magnetic fields to focus proton and heavy ion beams presented difficulties for the initial stages of the accelerator. Because the [[Lorentz force|magnetic force]] is dependent on the particle velocity, it was desirable to create a type of accelerator which could simultaneously accelerate and focus low-to-mid energy [[hadron|hadrons]].<ref>{{cite journal |last1=Stokes |first1=Richard H. |last2=Wangler |first2=Thomas P. |title=Radiofrequency Quadrupole Accelerators and their Applications |journal=Annual Reviews of Nuclear and Particle Science |date=1988 |volume=38 |pages=97-118 |url=https://www.annualreviews.org/doi/pdf/10.1146/annurev.ns.38.120188.000525 |access-date=3 February 2022}}</ref> In 1970, Soviet physicists I. M. Kapchinsky and [[Vladimir Teplyakov]] proposed the [[Radio-frequency quadrupole|radio-frequency quadrupole (RFQ)]] type of accelerating structure. RFQs use vanes or rods with precisely designed shapes in a resonant cavity to produce complex electric fields. These fields provide simultaneous acceleration and focusing to injected particle beams.<ref name = "Reiser 2008, p6">{{cite book |title= Theory and design of charged particle beams |last1= Reiser |first1= Martin |edition = 2nd |date= 2008 |publisher= [[Wiley-VCH]] |___location= Weinheim |isbn= 9783527407415 |page=6 |url= https://books.google.com/books?id=eegK9Mqgpi4C}}</ref>
==Construction and operation==
| |||