Bending magnet source

A comparison (Walker 1986) can be made of the flux and brightness produced by an undulator at its fundamental on-axis wavelength, A, to the peak value of a bending magnet source, i.e. the flux ratio is... 

The vertical opening angle, above and below the plane of the orbit defines a cone of synchrotron radiation from a bending magnet source that is a function of / c). r (the RMS half opening angle) can be approximately expressed as (Krinsky et al. 1983 Green 1975 Kim 1986)... 

Figure 7. The brightness function (H2(y)) and the flux function (G (y)) for a bending magnet source. Both functions fall slowly for energies less than the critical energy, and fall rapidly for energies above the critical energy.

In a practical case, using a bending magnet source this quantity is a function of the wavelength X and varies with the characteristics of the optical elements and with the horizontal angle of acceptance. The latter is determined by the... 

Bulk and micro-XAFS analyses were performed at the PNC-CAT s bending magnet (20-BM) and undulator (20-ID) beamlines of the Advanced Photon Source (APS), Argonne, IL, USA. Other microanalytical and mineralogical characterization studies were conducted at CANMET. Details of the methodology can be found in Paktunc (2008) and other publications by the author. 

S)mchrotron X-ray sources include both bending magnets and insertion devices. For protein crystallography, an undulator insertion device is preferred because it provides greater intensity at a specific wavelength and has lower beam divergence. This latter property results in smaller X-ray reflections. 

The X-ray source may be a conventional sealed tube or rotating anode generator or bending magnet synchrotron radiation and more recently the exploitation of multipole insertion devices such as wigglers and undulators represent great gains in source intensity. 

Fig. 3 Calculations of the beam in the horizontal plane from the source at bottom right through to a focus after the second bending magnet.

The photon sources from synchrotrons range from bending magnets, to wig-glers and undulators. The specific device used depends on the frequency range and brightness required for the specific application. 

Figure 2.7. Schematic diagram of a synchrotron illustrating x-ray radiation output from bending magnets. Electrons must be periodically injected into the ring to replenish losses that occur during normal operation. Unlike in conventional x-ray sources, where both the long-and short-term stability of the incident photon beam are controlled by the stability of the power supply, the x-ray photon flux in a synchrotron changes with time it decreases gradually due to electron losses, and then periodically and sharply increases when electrons are injected into the ring.

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