Search for liquids electrospraying the smallest possible nanodrops in vacuo
R. Alonso-Matilla, J. Fernandez-Garcia, H. Congdon, J. Fernández de la Mora*
Published in J. Appl. Phys: DOI: 10.1063/1.4901635, November 2014
Supplementary information
This document collects many of the original TOF spectra and corresponding propulsive
characteristics obtained for the various materials electrosprayed.
PR=reservoir pressure (Torr). Ie =spray current at the emitter (nA). ϕe=voltage on the tip
in positive mode unless otherwise noted (V). Q̇ TOF =liquid flow rate emitted based on TOF
curves (pl/s). Q̇POIS =liquid flow rate emitted based on PR and Poiseuille’s law (pl/s). T,
ϕe=thrust at emission voltage (nN). Isp, ϕe=specific impulse at emission voltage (s),
P=propulsive efficiency (%).
a
Components of the mixture
La (mm)
Related Figure and Table
EAN (90%) + MAN (10%)
211
A1
EAN (80%) + MAN (20%)
211
A2
EAN (75%) + MAN (25%)
211
A3
EAN (70%) + MAN (30%)
211
A4
EMI-BF4 (40%) + Sulfolane (60%)
169
B1
EMI-BF4 (60%) + Sulfolane (40%)
169
B2
EMI-BF4 (80%) + Sulfolane (20%)
169
B3
Pure EAN
169
C1
EAN (90%) + Sulfolane (10%)
169
C2
EAN (80%) + Sulfolane (20%)
154
C3
EAN (70%) + Sulfolane (30%)
154
C4
EAN (60%) + Sulfolane (40%)
154
C5
EAN (50%) + Sulfolane (50%)
154
C6
EAN (40%) + Sulfolane (60%)
154
C7
EAN (20%) + Sulfolane (80%)
154
C8
EMI-N(CN)2 (90%) + Sulfolane (10%)
154
D1
EMI-N(CN)2 (80%) + Sulfolane (20%)
154
D2
EMI-N(CN)2 (70%) + Sulfolane (30%)
154
D3
EMI-N(CN)2 (40%) + Sulfolane (60%)
154
D4
EMI-N(CN)2 (10%) + Sulfolane (90%)
154
D5
EAN (90%) + EMI-N(CN)2 (10%)
154
E1
EAN (50%) + EMI-N(CN)2 (50%)
154
E2
EAN (20%) + EMI-N(CN)2 (80%)
154
E3
EAN (10%) + EMI-N(CN)2 (90%)
154
E4
L=Distance extractor-collector
1
Figure A1. TOF curves. EAN+MAN (10%MAN)
Table A1. TOF parameters. EAN+MAN (10%MAN)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
1085
1185
2020
372.9
650.9
1042
235.6
55.9
710
1010
2020
267.8
423.5
853
268.5
60.1
560
939
2020
224.5
332.6
762
286.1
61.2
410
855
2020
186.2
241.6
675
305.5
63.0
335
814
2020
159.3
196.1
611
323.5
63.3
260
760
2020
129.8
150.7
534
347.1
63.3
185
710
2020
94.9
105.2
440
390.5
62.5
147.5
677
2020
79.8
82.4
389
410.9
60.7
110
630
2020
56.2
59.7
313
469.7
59.8
100
615
2020
48.4
53.6
286
497.9
59.2
90
600
2020
42.4
47.6
262
519.4
57.9
80
585
2020
36.5
41.5
239
551.6
57.5
70
565
2020
31.8
35.4
217
575.9
56.3
60
540
2020
27.4
29.4
196
604.3
55.9
2
Figure A2. TOF curves. EAN+MAN (20%MAN)
Table A3. TOF parameters. EAN+MAN (20%MAN)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
710
1300
2240
376.4
423.5
1146
256.8
55.0
560
1155
2040
280.2
332.6
900
270.9
56.1
410
1040
2040
216.4
241.6
768
299.3
58.2
335
957
2020
183.3
196.1
683
314.4
59.3
260
870
2020
138.9
150.7
570
346.3
59.5
185
845
2020
113.1
105.2
504
376.1
58.6
147.5
808
2020
91.7
82.4
441
405.5
57.7
110
743
2020
57.7
59.7
332
484.5
56.0
100
720
2020
50.5
53.6
304
506.8
55.3
90
705
2020
44.5
47.6
278
526.0
53.5
80
675
2020
39.0
41.5
254
550.2
53.3
70
660
2020
32.5
35.4
230
595.6
53.2
60
615
1970
25.6
29.4
195
640.8
53.4
50
580
1930
20.9
23.3
170
682.6
53.7
40
500
1930
17.9
17.2
145
684.5
52.7
3
Figure A3. TOF curves. EAN+MAN (25%MAN)
Figure A3. TOF parameters. EAN+MAN (25%MAN)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
710
560
410
335
260
185
147.5
110
100
90
80
70
60
50
3030
2060
1230
1140
1040
940
870
820
795
770
735
706
670
610
2230
2230
2150
2150
2150
2150
2150
2150
2150
2150
2150
2150
2150
2150
496.9
440.9
282.2
234.7
189.3
143.3
115.0
77.6
64.1
55.1
47.6
39.8
33.7
28.0
423.5
332.6
241.6
196.1
150.7
105.2
82.4
59.7
53.6
47.6
41.5
35.4
29.4
23.3
1589
1408
974
865
741
613
524
414
369
334
300
268
240
209
269.2
269.5
290.9
310.7
330.2
360.4
384.0
449.5
485.4
510.7
530.9
568.4
600.8
631.8
40.3
48.0
58.2
59.1
58.5
57.9
56.6
55.3
54.9
53.7
52.5
52.2
51.8
52.0
4
Figure A4. TOF curves. EAN+MAN (30%MAN)
Table A4. TOF parameters. EAN+MAN (30%MAN)
pR
Ie
e
QTOF
QPOIS
T @ e
Isp @ e
p)
710
560
410
335
260
185
147.5
110
100
90
80
70
60
50
2200
1525
1270
1208
1100
1005
940
870
837
805
750
650
575
500
1950
1950
1950
1950
1950
1950
1950
1950
1950
1950
1950
1950
1950
1950
592.8
484.0
320.6
253.6
197.8
153.5
118.8
76.9
68.6
58.8
50.2
44.2
34.2
30.8
423.5
332.6
241.6
196.1
150.7
105.2
82.4
59.7
53.6
47.6
41.5
35.4
29.4
23.3
1722
1544
1095
930
778
651
546
420
389
351
318
291
246
230
244.9
268.9
287.9
309.3
331.5
357.2
387.4
461.1
478.0
503.1
534.3
554.2
605.8
629.9
39.9
49.2
52.0
53.9
54.7
54.2
54.4
53.4
52.6
52.1
52.0
51.0
51.3
51.3
5
Figure B1. TOF curves. EMI-BF4+Sulfolane (40% IL)
Table B1. TOF parameters. EMI-BF4+Sulfolane (40% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
710
560
410
335
260
185
147.5
110
100
90
80
70
60
50
660
600
520
480
440
390
360
320
310
305
300
295
285
310
2690
2690
2690
2690
2690
2560
2560
2540
2540
2410
2410
2410
2410
2380
713.3
577.7
427.4
354.5
285.7
210.3
155.8
90.9
73.9
62.1
50.2
39.2
30.5
19.2
476.1
373.8
271.4
220.3
169.1
117.9
92.4
66.8
60.0
53.1
46.3
39.5
32.7
25.8
1478
1284
1044
928
803
635
522
370
329
287
252
213
178
130
166.8
178.8
196.5
210.5
226.2
242.9
269.6
327.2
358.8
371.8
404.5
436.4
470.6
547.2
76.2
77.2
78.5
80.4
81.0
81.1
79.7
77.3
77.8
75.3
73.2
67.6
63.1
50.3
6
Figure B2. TOF curves. EMI-BF4+Sulfolane (60% IL)
Table B2. TOF parameters. EMI-BF4+Sulfolane (60% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
1610
1085
860
710
560
410
335
260
185
147.5
110
100
90
80
770
660
605
580
527
470
460
425
395
390
400
430
450
480
2620
2540
2440
2400
2400
2400
2330
2330
2330
2330
2260
2260
2260
2230
940.0
711.9
614.0
527.2
422.3
323.6
289.7
206.0
150.0
123.1
67.1
60.8
51.3
40.3
852.3
572.3
452.3
372.3
292.2
212.2
172.2
132.2
92.2
72.2
52.2
46.9
41.5
36.2
1702
1388
1228
1124
968
816
751
601
488
435
299
282
254
227
145.7
156.9
160.8
171.6
184.6
202.9
208.7
234.3
262.4
284.5
360.1
373.7
399.6
451.5
67.5
70.4
72.1
74.5
75.3
77.5
77.2
74.7
72.7
71.1
62.4
57.2
52.7
50.9
7
Figure B3. TOF curves. EMI-BF4+Sulfolane (80% IL)
Table B3. TOF parameters. EMI-BF4+Sulfolane (80% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
1610
1085
710
560
410
335
260
185
147.5
110
100
90
80
70
1215
965
805
715
650
610
575
550
548
590
630
650
680
700
2650
2650
2510
2510
2510
2430
2430
2430
2430
2310
2550
2380
2380
2380
1219.4
888.7
666.9
514.6
431.7
348.9
277.8
206.8
172.1
116.0
112.9
99.4
92.3
90.8
697.8
468.5
304.8
239.3
173.7
141.0
108.2
75.5
59.1
42.7
38.4
34.0
29.6
25.3
2240
1776
1412
1196
1059
904
792
663
590
487
466
434
414
409
148
161
170
187
197
209
229
257
277
324
348
352
361
362
59.0
61.9
65.0
67.2
68.4
67.8
69.0
67.5
64.8
59.1
56.3
53.0
49.9
48.1
8
Figure C1. TOF curves. Pure EAN
Table C1. TOF parameters. Pure EAN
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
710
560
410
335
260
185
147.5
110
100
90
80
70
60
50
40
30
1550
1370
1060
980
880
800
755
680
650
615
605
590
565
545
515
420
2460
2460
2460
2460
2460
2460
2460
2320
2350
2340
2300
2310
2280
2270
2240
2270
517.7
403.4
272.0
237.7
170.7
136.0
114.1
62.3
54.2
46.4
40.2
33.6
26.5
20.4
13.6
8.3
435.3
341.8
248.3
201.6
154.8
108.1
84.7
61.3
55.1
48.9
42.6
36.4
30.2
23.9
17.7
11.5
1623
1374
1013
913
745
630
558
372
338
303
275
250
214
183
145
106
263
286
313
322.4
366.2
388.8
410.5
501.6
524
548.5
576
623
676
754
893
1074
62.4
64.0
64.9
64.8
66.3
65.1
64.3
61.4
60.1
59.6
58.8
58.8
57.8
57.4
57.6
60.7
9
Figure C2. TOF curves. EAN+Sulfolane (90% IL)
Table C2. TOF parameters. EAN+Sulfolane (90% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
860
710
560
410
335
260
185
147.5
110
100
90
80
60
50
856
780
717
660
620
568
530
503
490
450
415
400
250
220
2280
2440
2440
2310
2310
2310
2220
2170
2260
2260
2260
2100
2020
2100
304.1
270.5
221.4
165.1
136.8
108.7
69.9
63.2
58.1
50.9
45.5
21.4
9.4
5.4
564.8
465.0
365.1
265.2
215.3
165.4
115.4
90.5
65.5
58.8
52.2
45.5
32.2
25.6
941.5
885.6
771.5
628.1
553.6
469.9
357.7
327.3
312.3
278.9
252.7
157.5
80.5
57.9
259.9
274.8
292.4
319.3
339.8
362.8
429.6
434.4
450.6
460.1
465.9
618.8
719.2
909.5
66.9
67.4
67.5
68.8
68.4
67.3
67.6
67.3
65.4
64.7
64.1
59.4
57.8
57.2
10
Figure C3. TOF curves. EAN+Sulfolane (80% IL)
Table C3. TOF parameters. EAN+Sulfolane (80% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
710
560
410
335
260
185
147.5
110
100
90
80
70
60
543
515
480
460
440
430
420
427
425
424
422
400
410
1690
1690
1690
1690
1690
1690
1690
1720
1720
1720
1720
1720
1720
271.3
214.7
147.4
115.0
78.7
64.0
45.8
32.4
27.1
22.6
21.1
17.1
16.4
499.0
391.8
284.6
231.0
177.4
123.9
97.1
70.3
63.1
56.0
48.8
41.7
34.5
643.4
558.3
449.4
385.2
310.8
275.5
227.2
187.7
169.8
152.7
145.8
126.6
125.2
198.2
217.3
254.8
279.9
329.9
359.8
414.6
484.8
523.8
564.0
579.0
617.4
637.5
75.8
75.6
76.0
74.4
73.6
72.7
70.6
65.9
64.7
62.8
61.8
60.1
60.0
11
Figure C4. TOF curves. EAN+Sulfolane (70% IL)
Table C4. TOF parameters. EAN+Sulfolane (70% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
860
710
560
410
335
260
185
147.5
110
100
90
80
70
60
620
545
510
470
440
420
393
380
377
375
375
375
380
390
2970
2150
2150
2150
2150
2150
1870
1870
1870
1870
1870
1870
1870
1870
461.1
326.2
245.3
179.6
144.7
108.8
75.4
55.0
38.3
29.3
24.3
21.4
18.8
16.8
655.1
539.3
423.4
307.6
249.7
191.8
133.8
104.9
75.9
68.2
60.5
52.8
45.0
37.3
1199
807
680
558
490
403
309
256
210
181
163
151
141
134
206.0
230.9
258.9
282.3
308.7
341.9
387.9
455.6
514.3
558.1
587.0
623.8
663.9
670.8
62.8
63.9
64.6
66.1
67.8
69.3
71.0
73.3
75.6
72.0
76.7
75.3
75.8
75.5
12
Figure C5. TOF curves. EAN+Sulfolane (60% IL)
Table C5. TOF parameters. EAN+Sulfolane (60% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
1610
1085
860
710
560
410
335
260
185
147.5
100
90
80
70
60
50
40
30
655
570
520
470
430
400
380
350
330
330
310
350
350
355
360
350
330
300
2100
2100
2100
1950
1950
1950
1950
1870
1710
1710
1730
1640
1640
1640
1640
1640
1640
1640
695.6
483.8
391.8
323.7
243.3
177.0
143.7
100.5
66.8
52.1
25.7
21.9
18.3
14.3
11.8
8.9
7.1
5.0
1237.4
830.8
656.5
540.3
424.2
308.0
249.9
191.8
133.7
104.7
67.9
60.2
52.4
44.7
36.9
29.2
21.4
13.7
1291
1015
883
749
621
514
452
339
256
223
154
143
129
114
103
87
76
61
146.7
165.9
178.3
182.9
201.9
229.6
249.0
266.5
303.6
338.8
473.7
516.0
557.4
630.9
689.6
773.4
842.9
961.0
76.0
76.4
77.6
80.2
79.6
80.1
80.1
72.6
72.7
70.6
71.3
68.2
66.6
65.7
64.0
62.3
62.2
62.2
13
Table C6. TOF parameters. EAN+Sulfolane in negative mode (50% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
16
2280
260
2,16
3,83
44,68
1705,79
63,06
20
2280
280
2,80
7,49
51,88
1530,05
60,99
25
2280
305
3,52
12,07
59,54
1395,34
58,60
30
1930
320
3,42
16,65
54,54
1314,91
56,96
40
1930
375
5,70
25,80
73,78
1067,85
53,39
50
1930
365
9,16
34,96
91,78
826,99
52,85
60
1930
345
11,29
44,12
100,44
733,82
54,30
70
1930
330
15,44
53,27
116,86
624,26
56,18
90
1930
300
19,73
71,58
134,66
563,22
64,25
100
1930
290
22,52
80,74
143,99
527,50
66,56
197
2000
270
58,76
169,97
232,17
326,01
68,75
235
2000
265
78,75
204,31
268,93
281,77
70,13
310
2090
270
108,07
272,98
327,84
250,29
71,32
385
2090
300
143,98
341,66
420,84
241,16
79,39
460
2090
310
176,75
410,33
479,39
223,78
81,21
610
1930
350
254,32
547,69
588,54
190,93
81,60
760
1930
380
335,14
685,04
699,38
172,18
80,54
910
2040
413
413,26
822,39
835,45
166,80
81,13
1135
2040
450
533,09
1028,42
984,37
152,35
80,13
1660
2180
530
782,14
1509,15 1320,69
139,32
78,11
Table C7. TOF parameters. EAN+Sulfolane (40% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
2210
1610
1085
710
560
410
335
260
185
147.5
110
100
90
80
70
60
50
40
30
25
20
560
480
410
358
320
296
280
270
245
250
270
290
295
300
310
320
330
300
260
220
170
2370
2180
2180
2290
2210
2210
2370
2170
2070
2000
2080
2080
2070
2070
2070
2070
2070
2070
2070
2070
2070
1257.7
923.2
620.8
433.8
328.5
241.8
200.5
133.1
86.8
62.3
32.9
22.7
18.5
15.2
12.6
10.1
7.6
5.1
3.4
1.7
1.7
2217.9
1612.7
1083.1
704.8
553.5
402.1
326.5
250.8
175.2
137.3
99.5
89.4
79.3
69.2
59.2
49.1
39.0
28.9
18.8
13.8
8.7
1679
1284
988
796
644
542
490
374
266
218
166
143
130
117
108
97
86
67
49
38
28
114.6
119.4
136.7
157.7
168.3
192.2
209.8
241.8
262.3
299.3
435.4
539.4
594.7
661.3
720.4
802.9
929.7
1055.6
1389.1
1614
1801
81.9
82.0
82.9
82.3
81.8
84.4
81.5
81.3
72.4
68.8
67.9
68.0
67.7
66.5
65.0
63.4
63.2
60.7
66.9
70.6
73.5
14
Figure C6. TOF curves. EAN+Sulfolane (20% IL)
Table C8. TOF parameters. EAN+Sulfolane (20% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
2210
1610
1310
1085
860
710
560
410
335
297.5
415
365
340
305
285
255
230
205
195
185
2440
2440
2440
2440
2440
2360
2360
2210
2570
2440
1624.1
1220.6
978.0
808.7
650.3
520.6
423.7
297.4
268.7
212.3
2800.8
2036.4
1654.3
1367.7
1081.1
890.0
698.9
507.8
412.3
364.5
1634
1344
1162
1013
875
726
634
481
480
403
86.4
94.6
102.0
107.6
115.5
119.7
128.6
138.5
153.9
162.7
86.2
85.5
84.4
84.6
83.0
81.5
83.5
81.0
79.8
78.4
15
Figure D1. TOF curves. EMI-N(CN)2+Sulfolane (90% IL)
Table D1. TOF parameters. EMI-N(CN)2+Sulfolane (90% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
147.5
110
100
90
80
70
60
50
45
35
30
1900
1360
1270
1290
1310
1320
1360
1360
1380
1290
1250
2670
2300
2280
2280
2280
2280
2280
2280
2280
2280
2280
119.3
75.8
65.1
55.2
46.4
38.4
26.5
20.8
12.9
9.9
3.5
145.5
105.3
94.6
83.9
73.2
62.5
51.8
41.1
35.7
25.0
19.7
571
413
369
332
300
271.4
230.4
201.9
179.3
155.8
132.4
401.6
456.7
474.8
505.7
543.9
594.2
729.5
813.1
1162.2
1326.3
3131.1
22.4
29.8
29.9
28.3
27.1
26.5
26.8
26.2
32.8
34.8
72.0
16
Figure D2. TOF curves. EMI-N(CN)2+Sulfolane (80% IL)
Table D2. TOF parameters. EMI-N(CN)2+Sulfolane (80% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
260
185
147.5
110
70
60
50
44
40
35
1600
1000
850
730
630
670
740
810
850
900
2440
2230
2090
1990
1990
1990
1990
1990
1990
1990
246.3
202.9
168.0
101.1
53.6
41.2
32.9
26.2
18.0
14.2
277.8
193.9
152.0
110.0
65.3
54.1
42.9
36.2
31.7
26.1
877.8
756.2
622.5
437.5
288.8
243.6
212.9
184.7
151.7
139.6
297.9
309.7
311.4
361.7
449.9
494.4
541.0
588.9
702.2
820.5
33.2
52.2
53.6
53.8
51.1
44.6
38.6
33.3
31.1
31.6
17
Figure D3. TOF curves. EMI-N(CN)2+Sulfolane (70% IL)
Table D3. TOF parameters. EMI-N(CN)2+Sulfolane (70% IL)
pR
260
185
147.5
110
80
70
60
50
40
35
Ie
870
755
700
690
605
615
650
730
840
930
ϕe
2420
2340
2340
2340
2210
2210
2210
2210
2270
2270
QTOF
285.7
179.4
134.0
97.3
56.5
42.0
37.0
32.4
16.1
15.0
QPOIS
290.9
203.0
159.1
115.2
80.0
68.3
56.6
44.9
33.2
27.3
18
T @ ϕe
948.5
701.6
575
471.7
311.6
256.1
234.3
215.1
153
150.3
Isp @ ϕe
275.0
324.0
355.6
401.8
456.8
504.7
524.7
551.5
788.6
828.1
p (%)
61.2
63.5
61.6
57.9
52.5
46.9
42.2
36.3
31.3
29.2
Figure D4. TOF curves. EMI-N(CN)2+Sulfolane (40% IL)
Table D4. TOF parameters. EMI-N(CN)2+Sulfolane (40% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
710
560
410
335
260
185
147.5
110
90
80
70
60
50
930
804
702
648
575
508
470
418
390
350
275
250
275
2290
2250
2170
2170
2170
2170
2080
2080
1990
1990
1980
1890
1890
769.7
592.0
474.6
394.9
304.3
210.2
160.7
104.6
68.7
51.2
34.2
23.9
16.6
945.2
742.2
539.3
437.8
336.4
234.9
184.2
133.5
106.4
92.9
79.3
65.8
52.3
1575
1324
1114
987
822
646
530
409
305
247
174
133
110
169.3
185.1
194.2
206.7
223.4
254.3
272.7
323.7
367.2
399.1
420.5
463.4
548.7
69.9
74.4
77.1
78.1
78.3
78.6
77.7
79.5
75.2
73.2
68.7
66.8
59.6
19
Figure D5. TOF curves. EMI-N(CN)2+Sulfolane (10% IL)
Table D5. TOF parameters. EMI-N(CN)2+Sulfolane (10% IL)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
860
710
560
410
335
260
185
147.5
110
90
80
70
60
50
40
30
530
490
440
385
360
320
285
260
230
208
200
190
180
170
160
170
1770
1770
1770
1690
1650
1650
1650
1650
1690
1650
1650
1650
1650
1600
1600
1690
1283.0
1051.6
813.6
583.8
490.8
356.6
247.0
199.3
143.3
87.3
76.6
61.8
46.9
32.9
24.7
23.9
1370.9
1128.5
886.1
643.8
522.6
401.4
280.2
219.6
159.0
126.7
110.5
94.3
78.2
62.0
45.9
29.7
1574
1376
1155
899
786
636
493
428
343
244
224
196
160
128
109
108
103.0
109.8
119.2
129.3
134.6
149.7
167.4
180.4
200.5
234.3
244.9
265.7
288.1
327.8
364.3
376.6
86.7
87.3
88.4
89.2
88.8
89.7
87.2
89.4
87.7
82.6
82.4
82.2
77.0
76.2
76.2
70.6
20
Figure E1. TOF curves. EAN+EMI-N(CN)2 (90% EAN)
Table E1. TOF parameters. EAN+EMI-N(CN)2 (90% EAN)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
1610
1085
710
560
410
335
260
185
147.5
110
70
920
810
730
685
615
580
550
540
530
520
500
2030
2030
2030
2030
1870
1800
1800
1800
1800
1800
1870
564.3
409.3
280.1
224.0
157.2
128.9
89.2
71.1
58.0
37.8
23.5
819.6
550.4
358.1
281.2
204.3
165.8
127.4
88.9
69.7
50.5
30.0
1290
1047
830
718
552
472
372
321
283
212
156
192.7
215.7
249.7
270.5
295.7
308.9
352.3
380.8
411.8
473.6
560.5
66.5
68.5
69.6
69.5
70.5
69.4
65.8
62.5
60.7
53.3
46.4
21
Figure E2. TOF curves. EAN+EMI-N(CN)2 (50% EAN)
Table E2. TOF parameters. EAN+EMI-N(CN)2 (50% EAN)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
1610
860
560
335
185
147.5
90
70
60
860.00
755.00
690.00
620.00
590.00
575.00
580
590
585
2290
2290
2290
2290
2290
2330
2390
2390
2390
726.7
398.6
283.0
164.3
106.0
90.6
40.2
30.6
24.2
819.6
435.0
281.2
165.8
88.9
69.7
40.2
30.0
24.8
1538
1080
871
618
469
424
254
212
184
178.4
228.5
259.5
317.1
373.0
394.9
532.6
583.6
641.4
69.5
71.1
71.1
68.6
64.3
62.1
48.4
43.5
41.8
22
Figure E3. TOF curves. EAN+EMI-N(CN)2 (20% EAN)
Table E3. TOF parameters. EAN+EMI-N(CN)2 (20% EAN)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
410
335
185
80
70
60
40
30
890
870
704
680
700
730
750
710
2670
2670
2010
2220
2220
2220
2220
2220
292.4
236.2
134.6
63.7
52.8
44.4
26.5
16.7
275.4
223.5
119.9
47.3
40.4
33.5
19.7
12.7
1017
878
549
360
314
286
208
163
293.3
313.3
343.7
477.2
500.3
543.7
662.2
822.6
62.6
59.0
58.6
47.7
42.5
41.7
36.0
35.9
23
Figure E4. TOF curves. EAN+EMI-N(CN)2 (10% EAN)
Table E4. TOF parameters. EAN+EMI-N(CN)2 (10% EAN)
pR
Ie
ϕe
QTOF
QPOIS
T @ ϕe
Isp @ ϕe
p (%)
560
335
260
147.5
110
100
80
40
30
1230
967
940
865
885
905
940
900
826
2140
2140
2140
2140
2140
2140
2180
2180
2240
431.1
285.6
211.9
125.5
85.2
51.4
35.1
16.3
11.3
484.3
285.6
219.4
120.0
86.9
78.1
60.4
25.1
16.3
1.235
913
757
515
416
301
238
154
127
241.5
269.4
301.4
345.7
411.8
493.8
570.8
794.5
946.3
54.0
58.0
55.4
47.7
44.9
38.1
33.5
31.5
33.8
24
Studies with TBP/IL mixtures
In experiments prior to making the tip of the needle conductive, another gating approach
was used with TBP-based mixtures in the Time of Flight (TOF) apparatus. This method
introduced unnatural long-time tails in the TOF curves, due to unidentified electronic
problems which disappeared when directly pulsating the cone through the conductivized
needle. In these early studies the liquid was electrified through a platinum wire in contact
with the solution in the vial. Because gating the solution does not interrupt the spray fast
enough, the beam itself was gated at 1 kHz with a set of three grids placed on its path.
The central grid operated as an electrostatic gate. The other two grids and the extractor
were usually held at the same voltage Vo, at a polarity opposite to that of the spray, so as
to ease the discharge of the electrodes. The central grid deflected the particle beams
through a pulse generator module, similarly as with the conductivized needle. The voltage
at the emitter was determined by subtracting from the imposed vial voltage an estimated
voltage drop along the needle, in turn determined from the solution resistance within the
capillary and the measured spray current.
The first TOF study used EMI-Im 5% in TBP sprayed from a 555 mm long silica capillary
with an inner diameter of 73 microns. The Time of Flight waves for the different flow
rates studied and their associated operating conditions and propulsive parameters are
shown in Figure F1 and Table F1 respectively. Note the high propulsive efficiency
attained for all flow rates. The conductivity of the mixture was taken from reference [10]
to be K = 0.096 S/m, leading to an almost constant ϕe, in agreement with what would be
expected for a cone of fixed shape. The specific impulse is rather low, and even under
post-acceleration conditions remains below 250s.
25
Figure F1: Time of Flight waves for EMI-IM 5% in TBP.
Table F1: Operating conditions and propulsive parameters for EMI-IM 5% in TBP.
PR=reservoir pressure. VR=voltage in the reservoir. Ie=emitted current. ϕe=voltage on the
tip. ṁTOF =mass flow rate emitted based on TOF curves. T, ϕe=thrust at emission voltage.
ISP, ϕe=specific impulse at emission voltage. p=propulsive efficiency.
PR (Torr)
VR (V)
Ie (nA)
ϕe (V)
𝐦̇𝐓𝐎𝐅 (ng/s)
T, ϕe (nN)
ISP, ϕe (s)
p (%)
45.0
1620
136
1432
1224.48
669
55.7
93.8
40.0
1610
127
1435
1035.78
592
58.3
92.9
35.0
1590
117
1428
851.69
511
61.2
91.7
30.0
1580
106
1434
676.39
431
64.9
90.3
25.0
1560
93
1432
497.51
342
70.1
88.5
20.0
1540
78
1432
339.12
259
77.9
88.7
15.0
1540
58
1460
178.63
167
95.3
92.2
In our second study we mixed TBP with 10% EMI-N(CN)2, which is close to the
saturation concentration. The silica capillary had an inner diameter of 41 m and was 509
mm long. The experiments were mainly performed in positive polarity, but negative
polarity was also explored for a few values of the flow rate. The Time of Flight waves for
the series of flow rates analyzed and the associated operating conditions and propulsive
26
parameters are shown in Figures F2/F3 and Tables F2/F3 (for Positive/Negative polarity).
Again, the really high values of the propulsive efficiency (even higher than for EMI-Im)
are noteworthy. The conductivity of the solution (needed to determine the emission
voltage ϕe) was neither measured nor found in the literature, so a tentative value of 0.11
S/m was adopted to force ϕe to be as constant as possible over the whole range of (pR,VR)
used. As seen in the tables, the new solution resulted in a 50% improvement in the specific
impulse, reaching a still insufficient maximum value of around 125s (375s at 10kV total
acceleration voltage).
Figure F2: Time of Flight waves for EMI-N(CN)2 10% in TBP (positive polarity).
Table F2: Operating conditions and propulsive parameters of EMI-N(CN)2 10% in TBP
(positive polarity)
PR (Torr)
VR (V)
Ie (nA)
ϕe (V)
𝐦̇𝐓𝐎𝐅 (ng/s)
T, ϕe (nN)
ISP, ϕe (s)
p (%)
393.6
1760
195
1077
864.96
571
67.3
95.8
206.1
1600
135
1127
418.02
341
83.2
95.5
100.0
1500
105
1132
249.10
232
95.1
94.3
90.0
1480
99
1133
225.00
215
97.2
94.1
80.0
1440
93
1114
194.34
191
100.2
93.4
27
70.0
1420
87
1115
167.53
171
104.2
92.7
60.0
1380
80
1100
138.53
148
109.1
92.5
50.0
1355
72
1103
110.61
126
116.5
93.1
45.0
1340
69
1098
97.64
116
121.4
93.4
42.5
1310
66
1079
88.29
107
123.9
93.6
Figure F3: Time of Flight waves for EMI-N(CN)2 10% in TBP (negative polarity).
Table F3: Operating conditions and propulsive parameters of EMI-N(CN)2 10% in TBP
(negative polarity)
PR (Torr)
VR (V)
Ie (nA)
ϕe (V)
𝐦̇𝐓𝐎𝐅 (ng/s)
T, ϕe (nN)
ISP, ϕe (s)
p (%)
80.0
-1430
-93
-1104
191.35
0.191
101.8
92.9
60.0
-1370
-79
-1093
140.04
0.150
109.2
93.1
45.6
-1340
-66
-1109
105.58
0.122
117.5
95.8
We conclude that TBP combined with the new salts tested here is as inadequate for
propulsion applications as found in prior work with TBP/EMI-Im mixtures. TBP is
insufficiently polar to achieve the necessary room temperature electrical conductivities.
28