Electrostatic sweep plate devices have been used previously for the measurement of ion beam emittance. [ 11 These devices may be routinely designed with an ultimate angle resolution of B.25 mrad or less. We have used a similar device for measuring the emittance of H-and H+ beams exiting an RFQ at 1 MeV. This scanner will be used to characterize the beam exiting a low-power DTL at energies up to 2 MeV. The physics design changes consist primarily of increasing the length of the deflection plates and decreasing their separation to obtain high electric field at low deflection plate voltage. The front face of the scanner was made thicker and designed for water cooling to withstand the beam power at up to 2 MeV. In this paper the design of the scanner is discussed. This includes the device angular resolution and maximum acceptable angle. The thermal analysis that led to the design of the water-cooled front face is shown. Data showing the performance of the device and resulting emittance measurements at 1 MeV are presented.
Resonance lines of coronal ions of silicon are prominent in the spectral ranges 40–62 Å and 254–356 Å.An unexpected feature of the soft X-ray spectrum is the weakness or absence of the resonance lines of iron in ionization stages XI through XV.A second feature is the prominence of lines of the type (3d → 2p) relative to the resonance transitions (3p → 2s) in Li-like and Beryllium-like spectra. It is suggested that the upper levels (3d) are excited by quadrupole collisions from the ground 2s or 2s2levels.The intensity of the soft X-ray lines relative to the resonance lines in the 300 Å region seems to be more consistent with temperatures well above one million degrees than with temperatures as low as 700000°K, but the data are not adequate for a precise comparison. The relative intensity of the line emission from the various stages of silicon ionization may be interpreted as indicating that the ionization of silicon peaks in stages IX and X.The abundances of C, Mg, S, and Al relative to silicon do not seem to be greatly different from the chromospheric abundances reported by Pottasch or with the photospheric abundances.
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