Goals: There is a scintillation counter installed to detect hard x-rays. Gamma rays with a wavelength in the range from 0.1nm to 0.01nm are detected, this corresponds to energies from 12keV to 120keV. The goal is to detect electrons with high energy.
Runaway electrons Each electron is affected by the electric field and by collisions. The force of the electric field accelerates the electrons, whereas the friction force decelerate them. When the force of the electric field tops the friction force, the electron is accelerated. The cross section of collisions falls and the electron achieves almost a speed of light. As the electron is accelerated the radius of its trajectory increases. The electron emits photons due to synchrotron radiation, bremsstrahlung, collisions with the vessel (most electrons hit the limiter) Other sources of HXR The lower energy bounds of HXR can be used for detection of high-Z materials. Lines of heavy impurities in the H-like ionization state produce distinct peaks in the x-ray spectrum at given energies . Literature [1] WESSON, J., at.al. Tokamaks, Clarendon Press, Oxford, 2004, 3rd edition [2] KNOEPFEL, H. - SPONG, D.A. Runaway electrons in toroidal discharges. Nuclear fusion, 1979, vol.19, 785-829 [3] PEYSSON,Y. - IMBEAUX, F. Tomography of the fast electron bremsstrahlung emission during lower hybrid current drive on TORE SUPRA. Review of Scientific Instruments, 1999, vol. 70, No.10, 3987-4007 |
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