The characteristics of glow discharges in argon and other rare gases excited by an audio-frequency alternating potential and by a direct potential modulated with an audio-frequency signal are described. When the frequency of the alternating potential is of the same order of magnitude as the frequency of the spontaneous oscillations present in these gases excited with a direct potential, remarkable standing light patterns are observed. In all cases where the discharges are steady enough for detailed measurements striations are found that travel a fraction of the distance from the anode to the cathode in each cycle. At certain positions striations running from the cathode to the anode are also observed. Where the two types of striations meet they are nearly stopped for a time interval of the order of 10−4 second. There is electrical and optical evidence that a plasma exists for this time interval and that this plasma emits a continuous radiation. The behavior and occurrence of the discharges are correlated with a tentatively proposed mechanism.
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The zirconium electrodes are 1.5 cm long and have a square cross section
cm by
cm.
The iron electrodes are hollow cylinders 4 cm long and 1.2 cm diameter with a wall thickness of 0.1 cm.
These tubes are larger near the electrodes than in the middle.
Table II
Occurrence of standing ac discharges.
Tube
Frequency (ν, cps)
Current (rms ma)
Av. wavelength λ(cm)
2λν m/sec
dc Discharge
Krypton 4.5 mm
420
53
1.30
10.9
12–19 m/sec
700
40
2.04
28.6
600 cps
Neon 4.5 mm
3000
15.5
1.60
96.0
Unstable
4000
20
1.95
157
5000
16
2.17
218
6000
24
2.70
324
Mercury vapor
1000
7.5
1.50
30.0
35–52 m/sec
3500
19
1.30
91.0
2000–3100 cps
Argon 2.1 mm
3000
7.5
2.15
129
169–193 m/sec
6400
10
2.50
320
3000–5700 cps
Argon 4.4 mm
1760
47
3.13
110
140–220 m/sec
1760
24
2.94
103
2500–4000 cps
1900
38
3.29
125
1900
23
2.72
103
2000
21
2.78
111
2200
21
2.72
120
2400
21
2.75
132
Argon 12 mm
760
27.5
1.84
14.0
25–70 m/sec
810
28
1.82
14.5
1500–3800 cps
870
28
1.43
12.5
1000
12.5
0.80
8.0
1000
77
1.58
15.8
1200
15
1.59
19.1
1200
26
1.68
20.2
1250
26
1.75
21.9
1300
24.5
1.79
23.3
1400
15
1.63
22.8
1500
29
1.61
24.2
2000
25
1.29
16.6
2000
18
1.30
26.0
2200
25
1.16
25.5
2470
25
1.04
25.6
2780
26
1.37
38.1
Argon 30 mm
1300
39
0.54
14.0
25–45 m/sec
3000
34
0.33
19.8
2600–4300 cps
Table III
Range of current and frequency for standing modulated dc discharges.
The dc breakdown potential of this tube is 3800 volts,
Table V
Intensity of the continuum in a modulated dc discharge in argon 12 mm of Hg, 68 ma, 30% modulation, 3000 cps as a function of wavelength at two points of greatest color contrast. Iλ is the corrected intensity relative to undispersed light.
The zirconium electrodes are 1.5 cm long and have a square cross section
cm by
cm.
The iron electrodes are hollow cylinders 4 cm long and 1.2 cm diameter with a wall thickness of 0.1 cm.
These tubes are larger near the electrodes than in the middle.
Table II
Occurrence of standing ac discharges.
Tube
Frequency (ν, cps)
Current (rms ma)
Av. wavelength λ(cm)
2λν m/sec
dc Discharge
Krypton 4.5 mm
420
53
1.30
10.9
12–19 m/sec
700
40
2.04
28.6
600 cps
Neon 4.5 mm
3000
15.5
1.60
96.0
Unstable
4000
20
1.95
157
5000
16
2.17
218
6000
24
2.70
324
Mercury vapor
1000
7.5
1.50
30.0
35–52 m/sec
3500
19
1.30
91.0
2000–3100 cps
Argon 2.1 mm
3000
7.5
2.15
129
169–193 m/sec
6400
10
2.50
320
3000–5700 cps
Argon 4.4 mm
1760
47
3.13
110
140–220 m/sec
1760
24
2.94
103
2500–4000 cps
1900
38
3.29
125
1900
23
2.72
103
2000
21
2.78
111
2200
21
2.72
120
2400
21
2.75
132
Argon 12 mm
760
27.5
1.84
14.0
25–70 m/sec
810
28
1.82
14.5
1500–3800 cps
870
28
1.43
12.5
1000
12.5
0.80
8.0
1000
77
1.58
15.8
1200
15
1.59
19.1
1200
26
1.68
20.2
1250
26
1.75
21.9
1300
24.5
1.79
23.3
1400
15
1.63
22.8
1500
29
1.61
24.2
2000
25
1.29
16.6
2000
18
1.30
26.0
2200
25
1.16
25.5
2470
25
1.04
25.6
2780
26
1.37
38.1
Argon 30 mm
1300
39
0.54
14.0
25–45 m/sec
3000
34
0.33
19.8
2600–4300 cps
Table III
Range of current and frequency for standing modulated dc discharges.
The dc breakdown potential of this tube is 3800 volts,
Table V
Intensity of the continuum in a modulated dc discharge in argon 12 mm of Hg, 68 ma, 30% modulation, 3000 cps as a function of wavelength at two points of greatest color contrast. Iλ is the corrected intensity relative to undispersed light.