Jörg Hollandt, Michael Kühne, and Burkhard Wende, "High-current hollow-cathode source as a radiant intensity standard in the 40–125-nm wavelength range," Appl. Opt. 33, 68-74 (1994)
The radiant intensity of VUV emission lines of a high-current hollow-cathode source has been determined for the 40–125-nm spectral range. The source is operated at a constant current of 1 A with an aluminum cathode. Different rare gases are alternatively used as the buffer gas at pressures of ~ 100 Pa. The radiant intensity has been determined by comparison with the calculable spectral radiant flux of the electron storage ring BESSY. Radiant intensities of the emission lines are in the 7–1400-μW/sr range. The long-term reproducibility of the radiant intensity of the source is within ± 10% (2σ value). The systematic uncertainty of the radiometric calibration is better than 9%
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Hollow cathode parameters, 1 A, 500 V. Systematic relative uncertainty of the calibration procedure, < 9% (see Table 4). Long-term reproducibility of the source to within ± 10% (see Fig. 2).
Table 4
Contributions to the Systematic Relative Uncertainty of Radiant Intensity IHC for Two Differently Coated Imaging Mirrors in the Calibration Beam Line
Mirrors
Source of Uncertainty
SiC (%)
Os (%)
Spectral radiant flux of synchrotron radiation ΔΦλSR/ΦλSR0
1.3
1.3
Ratio of photocurrent Δ(iHC/iSR)/(iHC/iSR)
1.0 (75 nm)
3.0
4.0 (105 nm)
7.0
Polarization properties of the optical components and the detector ΔF/F
2.0
2.0
Solid angle of HC measurements ΔΩ/Ω
0.5
0.5
Reflectance variations over the imaging mirror surface Δr/r
1.0
0.3
Spatial coincidence of the fields of illumination of the HC and synchrotron radiation on the grating and the detector Δa/a
5.0
5.0
Overall systematic relative uncertainty of the radiant intensity ΔI/I
5.7 (75 nm)
6.3
6.9 (105 nm)
8.9
Long-term stability of the HC source (2σ value)
10.0
10.0
Tables (4)
Table 1
Purity and Typical Pressure of the Employed Buffer Gases when the HC Source was Operated at 1 A and 500 Va
Gas
Purity (%)
Pressure (Pa)
Helium
99.996
120
Neon
99.990
80
Argon
99.998
50
Krypton
99.998
60
Pressure was measured at the gauge port of the back anode.
Table 2
Radiant Intensity of the Ar i 106.67-nm Emission Line when the Beam Line was Calibrated with Different Optical Configurationsa
Hollow cathode parameters, 1 A, 500 V. Systematic relative uncertainty of the calibration procedure, < 9% (see Table 4). Long-term reproducibility of the source to within ± 10% (see Fig. 2).
Table 4
Contributions to the Systematic Relative Uncertainty of Radiant Intensity IHC for Two Differently Coated Imaging Mirrors in the Calibration Beam Line
Mirrors
Source of Uncertainty
SiC (%)
Os (%)
Spectral radiant flux of synchrotron radiation ΔΦλSR/ΦλSR0
1.3
1.3
Ratio of photocurrent Δ(iHC/iSR)/(iHC/iSR)
1.0 (75 nm)
3.0
4.0 (105 nm)
7.0
Polarization properties of the optical components and the detector ΔF/F
2.0
2.0
Solid angle of HC measurements ΔΩ/Ω
0.5
0.5
Reflectance variations over the imaging mirror surface Δr/r
1.0
0.3
Spatial coincidence of the fields of illumination of the HC and synchrotron radiation on the grating and the detector Δa/a
5.0
5.0
Overall systematic relative uncertainty of the radiant intensity ΔI/I