Editing Fusion power (section)

=== Measurement ===
{{Main|Flux loop|Langmuir probe|Neutron detection|Thomson scattering|X-ray detector}}

The diagnostics of a fusion scientific reactor are extremely complex and varied.<ref>{{Citation|title=Towards a fusion reactor|work=Nuclear Fusion|year=2002|publisher=IOP Publishing Ltd|doi=10.1887/0750307056/b888c9|isbn=0750307056|doi-access=free}}</ref> The diagnostics required for a fusion power reactor will be various but less complicated than those of a scientific reactor as by the time of commercialization, many real-time feedback and control diagnostics will have been perfected. However, the operating environment of a commercial fusion reactor will be harsher for diagnostic systems than in a scientific reactor because continuous operations may involve higher plasma temperatures and higher levels of neutron irradiation. In many proposed approaches, commercialization will require the additional ability to measure and separate diverter gases, for example helium and impurities, and to monitor fuel breeding, for instance the state of a tritium breeding liquid lithium liner.<ref>{{Citation|last1=Pearson|first1=Richard J|title=Review of approaches to fusion energy|date=2020|url=http://dx.doi.org/10.1088/978-0-7503-2719-0ch2|work=Commercialising Fusion Energy|publisher=IOP Publishing|access-date=December 12, 2021|last2=Takeda|first2=Shutaro|doi=10.1088/978-0-7503-2719-0ch2|isbn=978-0750327190|s2cid=234561187}}</ref> The following are some basic techniques.
* [[Flux loop]]: a loop of wire is inserted into the magnetic field. As the field passes through the loop, a current is made. The current measures the total magnetic flux through that loop. This has been used on the [[National Compact Stellarator Experiment]],<ref>{{Cite book|last1=Labik|first1=George|last2=Brown|first2=Tom|last3=Johnson|first3=Dave|last4=Pomphrey|first4=Neil|last5=Stratton|first5=Brentley|last6=Viola|first6=Michael|last7=Zarnstorff|first7=Michael|last8=Duco|first8=Mike|last9=Edwards|first9=John|last10=Cole|first10=Mike|last11=Lazarus|first11=Ed|title=2007 IEEE 22nd Symposium on Fusion Engineering |chapter=National Compact Stellarator Experiment Vacuum Vessel External Flux Loops Design and Installation |date=2007|chapter-url=https://ieeexplore.ieee.org/document/4337935|pages=1–3|doi=10.1109/FUSION.2007.4337935|isbn=978-1424411931|s2cid=9298179}}</ref> the [[polywell]],<ref>{{Cite journal|last1=Park|first1=Jaeyoung|last2=Krall|first2=Nicholas A.|last3=Sieck|first3=Paul E.|last4=Offermann|first4=Dustin T.|last5=Skillicorn|first5=Michael|last6=Sanchez|first6=Andrew|last7=Davis|first7=Kevin|last8=Alderson|first8=Eric|last9=Lapenta|first9=Giovanni|date=June 1, 2014|title=High Energy Electron Confinement in a Magnetic Cusp Configuration|journal=Physical Review X|volume=5|issue=2|pages=021024|arxiv=1406.0133|bibcode=2015PhRvX...5b1024P|doi=10.1103/PhysRevX.5.021024|s2cid=118478508}}</ref> and the [[Levitated dipole|LDX]] machines. A [[Langmuir probe]], a metal object placed in a plasma, can be employed. A potential is applied to it, giving it a [[voltage]] against the surrounding plasma. The metal collects charged particles, drawing a current. As the voltage changes, the current changes. This makes an [[Current–voltage characteristic|IV Curve]]. The IV-curve can be used to determine the local plasma density, potential and temperature.<ref>{{cite journal|last1=Mott-Smith|first1=H. M.|last2=Langmuir|first2=Irving|date=September 1, 1926|title=The Theory of Collectors in Gaseous Discharges|journal=Physical Review|publisher=American Physical Society (APS)|volume=28|issue=4|pages=727–763|bibcode=1926PhRv...28..727M|doi=10.1103/physrev.28.727|issn=0031-899X}}</ref>
* [[Thomson scattering]]: "Light scatters" from plasma can be used to reconstruct plasma behavior, including density and temperature. It is common in [[Inertial confinement fusion]],<ref>{{cite journal | last1=Esarey | first1=Eric | last2=Ride | first2=Sally K. | last3=Sprangle | first3=Phillip | title=Nonlinear Thomson scattering of intense laser pulses from beams and plasmas | journal=Physical Review E | publisher=American Physical Society (APS) | volume=48 | issue=4 | date=September 1, 1993 | issn=1063-651X | doi=10.1103/physreve.48.3003 | pmid=9960936 | pages=3003–3021| bibcode=1993PhRvE..48.3003E }}</ref> [[Tokamak]]s,<ref>{{Cite journal |last1=Kantor |first1=M. Yu |last2=Donné |first2=A. J. H. |last3=Jaspers |first3=R. |last4=van der Meiden |first4=H. J. |date=February 26, 2009 |title=Thomson scattering system on the TEXTOR tokamak using a multi-pass laser beam configuration |url=https://iopscience.iop.org/article/10.1088/0741-3335/51/5/055002 |journal=Plasma Physics and Controlled Fusion |language=en |volume=51 |issue=5 |pages=055002 |bibcode=2009PPCF...51e5002K |doi=10.1088/0741-3335/51/5/055002 |issn=0741-3335 |s2cid=123495440}}</ref> and [[fusor]]s. In ICF systems, firing a second beam into a gold foil adjacent to the target makes x-rays that traverse the plasma. In tokamaks, this can be done using mirrors and detectors to reflect light.
* [[Neutron detection|Neutron detectors]]: [[Neutron detection#Types of neutron detectors|Several types of neutron detectors]] can record the rate at which neutrons are produced.<ref>{{Cite book|last=Tsoulfanidis|first=Nicholas|url=http://archive.org/details/measurementdetec00tsou|title=Measurement and detection of radiation|date=1995|publisher=Washington, DC : Taylor & Francis|others=Library Genesis|isbn=978-1560323174}}</ref><ref>{{Cite book|last=Knoll, Glenn F. |title=Radiation detection and measurement|date=2010|publisher=John Wiley|isbn=978-0470131480|edition=4th|location=Hoboken, NJ|oclc=612350364}}</ref>
* [[X-ray detectors]] Visible, IR, UV, and X-rays are emitted anytime a particle changes velocity.<ref>{{Cite journal|last=Larmor|first=Joseph|date=January 1, 1897|title=IX. A dynamical theory of the electric and luminiferous medium. Part III. relations with material media|journal=Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character|volume=190|pages=205–300|doi=10.1098/rsta.1897.0020|bibcode=1897RSPTA.190..205L|doi-access=free}}</ref> If the reason is deflection by a magnetic field, the radiation is [[cyclotron]] radiation at low speeds and [[synchrotron]] radiation at high speeds. If the reason is deflection by another particle, plasma radiates X-rays, known as [[Bremsstrahlung]] radiation.<ref>{{Cite book |title=Diagnostics for experimental thermonuclear fusion reactors 2|date=1998|publisher=Springer |veditors=Stott PE, Gorini G, Prandoni P, Sindoni E |isbn=978-1461553533|location=New York|oclc=828735433}}</ref>