R. C. Isler and R. A. Langley, "Relative calibration of grazing incidence spectrometers from charge-exchange excitation of hydrogenic ions," Appl. Opt. 24, 254-260 (1985)
Charge transfer from hydrogen atoms having energies below 35 keV to fully ionized low-Z impurities takes place predominantly in two excited levels. It is shown that the subsequent radiative cascades from C5+, N6+; and O7+ can be used to obtain the relative response of grazing incidence spectrometer systems in the region between 102 and 1164 Å. In principle, the technique can be extended to 19 Å. The method is useful in plasma devices employing neutral beams for heating or for diagnostic probing. The absolute sensitivity of a system is then established by normalizing to only one branching ratio measurement from a pair of lines having accurately known transition probabilities. Results from the Impurity Studies Experiment-B (ISX-B) tokamak are presented.
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Charge-Transfer Cross Sections into the Excited Levels of O7+ (10−16cm2)from Ref. 12
Hydrogen Energy (keV)
n level
4
5
6
7
35.2
2.88
21.54
22.86
2.66
17.5
4.80
31.55
20.30
2.23
12.15
5.31
36.12
20.20
1.34
1.35
0.26
47.24
14.98
0.19
Table II
Effective CXE Cross Sections for O VII Excitation Normalized to the n = 5 → n = 4 transition (Absolute Cross Sections in Units of 10−15 cm2 are Shown in Parentheses)
Effective CXE Cross Sections for C VI Excitation Normalized to the n = 4 → n = 3 Transition (Absolute Cross Sections in Units of 10−15 cm2 are Shown in Parentheses)
Ref. 11. Ref. 15.
Total n-level cross sections from Ref. 11 with assumption of statistical l-level excitation.
Table IV
Effective CXE Cross Sections for N VII Excitation Normalized to the n = 4 → n = 3 Transition22 (Absolute Cross Sections in Units of 10−15 cm2 are Shown in Parentheses)
Transition (Å)
Energy (keV) 32.0
Δn = 1
5—4 (826)
0.57
4—3 (382)
1.00
3—2 (134)
(1.84) 1.11
2—1 (24.8)
1.42
Δn = 2
6—4 (536)
0.06
5—3 (261)
0.15
4—2 (99.1)
0.26
3—1 (20.9)
0.13
Table V
Relative Intensities of the Δn = 1 Transitions of O VIII and C VI Calculated for Various Assumptions About Populations and State Mixinga
These values are weighted for equal beam currents and a 20% correction for the thermalized halo atoms. Total n-level cross sections are from Refs. 11 and 12 for all cases. l-level cross sections from Refs. 11 and 12. l-level excitation assumed statistical.
Complete Stark mixing using transition probabilities from Ref. 16, statistical excitation. lj and l + 1j states equally mixed, statistical excitation.
Tables (5)
Table I
Charge-Transfer Cross Sections into the Excited Levels of O7+ (10−16cm2)from Ref. 12
Hydrogen Energy (keV)
n level
4
5
6
7
35.2
2.88
21.54
22.86
2.66
17.5
4.80
31.55
20.30
2.23
12.15
5.31
36.12
20.20
1.34
1.35
0.26
47.24
14.98
0.19
Table II
Effective CXE Cross Sections for O VII Excitation Normalized to the n = 5 → n = 4 transition (Absolute Cross Sections in Units of 10−15 cm2 are Shown in Parentheses)
Effective CXE Cross Sections for C VI Excitation Normalized to the n = 4 → n = 3 Transition (Absolute Cross Sections in Units of 10−15 cm2 are Shown in Parentheses)
Ref. 11. Ref. 15.
Total n-level cross sections from Ref. 11 with assumption of statistical l-level excitation.
Table IV
Effective CXE Cross Sections for N VII Excitation Normalized to the n = 4 → n = 3 Transition22 (Absolute Cross Sections in Units of 10−15 cm2 are Shown in Parentheses)
Transition (Å)
Energy (keV) 32.0
Δn = 1
5—4 (826)
0.57
4—3 (382)
1.00
3—2 (134)
(1.84) 1.11
2—1 (24.8)
1.42
Δn = 2
6—4 (536)
0.06
5—3 (261)
0.15
4—2 (99.1)
0.26
3—1 (20.9)
0.13
Table V
Relative Intensities of the Δn = 1 Transitions of O VIII and C VI Calculated for Various Assumptions About Populations and State Mixinga
These values are weighted for equal beam currents and a 20% correction for the thermalized halo atoms. Total n-level cross sections are from Refs. 11 and 12 for all cases. l-level cross sections from Refs. 11 and 12. l-level excitation assumed statistical.
Complete Stark mixing using transition probabilities from Ref. 16, statistical excitation. lj and l + 1j states equally mixed, statistical excitation.