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| | Hi there, I am Alyson Pomerleau and I think it sounds fairly good when you say it. To climb is something she would by no means give up. Mississippi is exactly where his house is. I am an invoicing officer and I'll be promoted soon.<br><br>Visit my website - tarot readings ([http://clip.nguoimiennui.com/profile.php?u=MoHibbs http://clip.nguoimiennui.com/profile.php?u=MoHibbs]) |
| '''Electron cyclotron resonance''' is a phenomenon observed in [[plasma physics]], [[condensed matter physics]], and [[accelerator physics]]. An [[electron]] in a static and uniform [[magnetic field]] will move in a circle due to the [[Lorentz force]]. The circular motion may be superimposed with a uniform axial motion, resulting in a [[helix]], or with a uniform motion perpendicular to the field, e.g., in the presence of an electrical or gravitational field, resulting in a [[cycloid]]. The [[angular frequency]] (ω = 2π[[Frequency|''f'']] ) of this ''cyclotron'' motion for a given magnetic field strength ''B'' is given (in [[SI]] units)<ref>In SI units, the elementary charge ''e'' has the value 1.602×10<sup>-19</sup> [[coulomb]]s, the mass of the electron ''m'' has the value 9.109×10<sup>–31</sup> kilograms, the magnetic field ''B'' is measured in [[tesla (unit)|tesla]]s, and the angular frequency ω is measured in [[radian]]s per [[second]].</ref> by
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| :<math>\omega_{ce}=\frac{eB}{m}</math>.
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| where <math>e</math> is the [[elementary charge]] and <math>m</math> is the mass of the electron. For the commonly used [[microwave]] frequency [[ISM band|2.45 GHz]] and the bare electron charge and mass, the resonance condition is met when ''B'' = 875 [[gauss (unit)|G]] = 0.0875 [[tesla (unit)|T]]. | |
| For particles of charge ''q'', rest mass ''m''<sub>0</sub> moving at relativistic speeds ''v'', the formula needs to be adjusted according to the [[special theory of relativity]] to:
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| :<math>\omega_{ce}=\frac{qB}{\gamma\cdot m_0}</math>
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| where
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| :<math>\gamma=\frac{1}{\sqrt{ 1 - (v/c)^2 }}</math>.
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| ==In plasma physics==
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| An ionized [[Plasma (physics)|plasma]] may be efficiently produced or heated by superimposing a static [[magnetic field]] and a high-frequency [[electromagnetic field]] at the electron cyclotron [[resonance]] frequency. In the toroidal magnetic fields used in [[magnetic fusion energy]] research, the magnetic field decreases with the major radius, so the location of the power deposition can be controlled within about a centimeter. Furthermore, the heating power can be rapidly modulated and is deposited directly into the electrons. These properties make electron cyclotron heating a very valuable research tool for energy transport studies. In addition to heating, electron cyclotron waves can be used to drive current. The inverse process of [[Cyclotron radiation|electron cyclotron emission]] can be used as a [[Plasma diagnostics|diagnostic]] of the radial electron temperature profile.
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| ==ECR ion sources==
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| Since the early 1980s, following the [[Tom W. Bonner Prize|award-winning]] pioneering work done by Dr. [[Richard Geller]],<ref>R. Geller, Peroc. 1st Int. Con. Ion Source, Saclay, p. 537, 1969</ref> Dr. [[Claude Lyneis]], and Dr. H. Postma;<ref>H. Postma, Phys. Lett. A, 31, p. 196, 1970</ref> respectively from [[Commissariat à l'Énergie Atomique|French Atomic Energy Commission]], [[Lawrence Berkeley National Laboratory]] and the [[Oak Ridge National Laboratory]], the use of electron cyclotron resonance for efficient plasma generation, especially to obtain large numbers of multiply charged ions, has acquired a unique importance in various technological fields. Many diverse activities depend on electron cyclotron resonance technology, including
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| * advanced cancer treatment, where ECR [[ion sources]] are crucial for [[proton therapy]],
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| * advanced [[Semiconductor fabrication|semiconductor manufacturing]], especially for high density [[DRAM]] memories, through [[plasma etching]] or other [[plasma processing]] technologies,
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| * [[Electrically powered spacecraft propulsion|electric propulsion]] devices for [[spacecraft propulsion]], where a broad range of devices ([[HiPEP]], some [[Electrostatic ion thruster|ion thruster]]s, or [[electrodeless plasma thruster]]s),
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| * for [[particle accelerator]]s, on-line mass separation and radioactive ion charge breeding,<ref>''Handbook of Ion Source,'' B. Wolf, ISBN 0-8493-2502-1, p136-146</ref>
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| * and, as a more mundane example, painting of plastic bumpers for cars.
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| The ECR ion source makes use of the electron cyclotron resonance to ionize a plasma. Microwaves are injected into a volume, at the frequency corresponding to the electron cyclotron resonance defined by a magnetic field applied to a region inside the volume. The volume contains a low pressure gas. The alternating electric field of the microwaves being synchronous with the gyration period of the free electrons of the gas, it increases their perpendicular kinetic energy. When in turn the energized free electrons collide with the atoms or molecules of the gas in the volume and cause ionization, if their kinetic energy is larger than the molecule or atom ionization energy. The ions produced correspond to the gas type used. The gas may be pure, a compound gas, or can be a vapor of a solid or liquid material.
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| ECR ion sources are able to produce singly charged ions with high intensities (e.g. [[Hydrogen|H]]<sup>+</sup> and [[Deuterium|D]]<sup>+</sup> ions of more than 100 [[milliampere|mA]] (electrical) in DC mode<ref>R. Gobin et al., [http://accelconf.web.cern.ch/AccelConf/e02/PAPERS/THPRI003.pdf Saclay High Intensity Light Ion Source Status] The Euro. Particle Accelerator Conf. 2002, Paris, France, June 2002, p1712</ref> using a 2.45 GHz ECR ion source).
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| For multiply charged ions, the ECR ion source has the advantage that it is able to confine the ions for long enough for multiple collisions to take place (leading to multiple ionization) and that the low gas pressure in the source avoids recombination. The VENUS ECR ion source at [[Lawrence Berkeley National Laboratory]] has produced in intensity of 0.25 mA (electrical) of [[Bismuth|Bi]]<sup>29+</sup>.<ref>[http://cerncourier.com/cws/article/cern/29329 VENUS reveals the future of heavy-ion sources] CERN Courier, 6 May 2005</ref>
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| Some of these industrial fields would not even exist without the use of this fundamental technology, which makes electron cyclotron resonance ion and plasma sources one of the enabling technologies of today's world.
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| ==In condensed matter physics==
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| Within a solid the mass in the cyclotron frequency equation above is replaced with the [[effective mass (solid-state physics)|effective mass]] tensor <math>\begin{Vmatrix}m^*\end{Vmatrix}</math>. Cyclotron resonance is therefore a useful technique to measure [[effective mass (solid-state physics)|effective mass]] and [[Fermi surface]] cross-section in solids. In a sufficiently high magnetic field at low temperature in a relatively pure material
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| <math>\begin{matrix}\omega_{ce} > 1/\tau \\
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| \hbar \omega_{ce} > k_B T \\
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| \end{matrix}</math>
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| where <math>\tau</math> is the carrier scattering lifetime, <math>k_B</math> is [[Boltzmann's constant]] and <math>T</math> is temperature. When these conditions are satisfied, an electron will complete its cyclotron orbit without engaging in a collision, at which point it is said to be in a well-defined [http://www.warwick.ac.uk/~phsbm/2deg.htm#ll Landau level].
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| ==See also==
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| * [[Cyclotron resonance]]
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| * [[Cyclotron]]
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| * [[ARC-ECRIS]]
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| * [[Ion cyclotron resonance]]
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| * [[Synchrotron]]
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| * [[Gyrotron]]
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| * [[De Haas-van Alphen effect]]
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| ==References==
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| {{Reflist}}
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| ==Further reading==
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| * [http://mgm.mit.edu/historic/i1101.pdf "Personal Reminiscences of Cyclotron Resonance,"] G. Dresselhaus, Proceedings of ICPS-27 (2004). This paper describes the early history of cyclotron resonance in its heyday as a [[band structure]] determination technique.
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| {{DEFAULTSORT:Electron Cyclotron Resonance}}
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| [[Category:Waves in plasmas]]
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| [[Category:Condensed matter physics]]
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| [[Category:Electric and magnetic fields in matter]]
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| [[Category:Ion source]]
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| [[Category:Particle accelerators]]
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Hi there, I am Alyson Pomerleau and I think it sounds fairly good when you say it. To climb is something she would by no means give up. Mississippi is exactly where his house is. I am an invoicing officer and I'll be promoted soon.
Visit my website - tarot readings (http://clip.nguoimiennui.com/profile.php?u=MoHibbs)