Fig. 1.
![Normalized electron thermionic emission current of a dispenser cathode operating at 1373.2 K as a function of metal temperature (based on [10, 11])](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/694828ee7c29e05adc524c36/j_ama-2025-0072_fig_001.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKB6JPJ4IZ%2F20260225%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260225T161021Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEEQaDGV1LWNlbnRyYWwtMSJHMEUCIHhv10Z7nO7YqDTi8wtzJH7COmtSv%2BOAEgEKdAzIyfKEAiEA4mJK1%2F2voErlvET3qYn2JQZpjBGOZOKV5jybVBw8Iy4qvAUIDRACGgw5NjMxMzQyODk5NDAiDCk0eNQI0aH9UhOBUSqZBQccYCExbh8%2BahzenU72hQ7RE66Jh1KQow0a%2F78mVcc5Wa%2Bwiym3Hc33raHHKENgJYQQLZqTkoFa76X6ICDI3GledJGqHTGtQAwPxmY9OiJ%2BjaxgZhwEz%2BQyG4nvju3P2KIIbCATwQHGxk2Akqpx%2Bopzzkrdx7E4rQNDyC%2BWMuChoeMh7ufwDYKu8IdfVQP6PZIJg%2FvS7wlVM2o75HrdjkGc2tI6MEu1OZokHmjdlDi7PxBSd%2Fgi%2FeqLL28eu9hEWTVPAgS3StbFzEE0afO68MGcQfGwzhBXX6a%2BAUWPjPSyfvhgpOmH7D3LTiQWbQpiRoM10f6Vxc9ndLXupq6kzVGLYGL0s0gOHrwIN5A%2FBE3Jbl%2FCeL6B7HUylIvuc0myu88Sj8BNV9bzOtk2qbcaGFC6XKAzFLtTibgo0r6Evn788u3ZiScuIXudGvIYO1MUUrmzJCQ53tn6YGlE2k7gey3WJjMBV9l04VMFnNq5XEQe2ckYICnZ72EZMYegvgAiyKFDzKSv2KY%2FgennvtTyc4d3cmxXfuQA6k8EOmOLj0i6VV31pZgDya2iWqUli7V18D0gt%2BiqYKMT2LffT3V83ExwT8BL4SxlSmsUxA0diEUvaDLjUEAeOJLyEG%2FF77RY9lwsoPGfUegfBb%2FNt8rM9Az6qwR%2FkqkrpvPTxHGFEbOSpaRN%2FwiTSCDdgGqWO9ydueuwqFZgO46JPJrr4byXLZeseXBFarAo9O2mHNk3syA%2BQk%2BzYTCG%2B17%2FQ5jeWLWEtg3NsRKeIZAtU5q2onCXHDMywdCinKdN8oven2gFm5pARD6LVSPk8UDX1vQKje21UqR0B3cVmpykkQwlBN7TjgHkZlNmwD6rrB%2BtvXPYZFNPFD2ljVeOsFvgMJ3Q%2B8wGOrEB8sKxYXxhskvwjH1dGOxfLztLc3I3gXWeVwdwUK6YbhjgVBpDMrWg3XTQDoMwRKlclO%2BgXl6QnIPg5RLtpPOQWN8SW4VFyMZ5vYsshGenMOKoXHkNdk3xcgh1AasKFXGrsV%2FqOD2QvLlxweT0TS9HeLV%2F8DecrCfy%2FR63MzBOJzX%2F3Is5SkhHk%2Fp2rK%2FqIq%2FTbdcZynEs9BVnjt4V6wVy2vlkyhl3otJSkz55vAzoKUAO&X-Amz-Signature=4be211caf5c356cb21b249e6b30c1314013318b2aaa8b2a0c7696bfc5a5a01ec&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 2.
![Normalized electron thermionic emission current of a dispenser cathode operating at 1373.2 K as a function of metal vapor pres-sure (based on [10, 11])](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/694828ee7c29e05adc524c36/j_ama-2025-0072_fig_002.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKB6JPJ4IZ%2F20260225%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260225T161021Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEEQaDGV1LWNlbnRyYWwtMSJHMEUCIHhv10Z7nO7YqDTi8wtzJH7COmtSv%2BOAEgEKdAzIyfKEAiEA4mJK1%2F2voErlvET3qYn2JQZpjBGOZOKV5jybVBw8Iy4qvAUIDRACGgw5NjMxMzQyODk5NDAiDCk0eNQI0aH9UhOBUSqZBQccYCExbh8%2BahzenU72hQ7RE66Jh1KQow0a%2F78mVcc5Wa%2Bwiym3Hc33raHHKENgJYQQLZqTkoFa76X6ICDI3GledJGqHTGtQAwPxmY9OiJ%2BjaxgZhwEz%2BQyG4nvju3P2KIIbCATwQHGxk2Akqpx%2Bopzzkrdx7E4rQNDyC%2BWMuChoeMh7ufwDYKu8IdfVQP6PZIJg%2FvS7wlVM2o75HrdjkGc2tI6MEu1OZokHmjdlDi7PxBSd%2Fgi%2FeqLL28eu9hEWTVPAgS3StbFzEE0afO68MGcQfGwzhBXX6a%2BAUWPjPSyfvhgpOmH7D3LTiQWbQpiRoM10f6Vxc9ndLXupq6kzVGLYGL0s0gOHrwIN5A%2FBE3Jbl%2FCeL6B7HUylIvuc0myu88Sj8BNV9bzOtk2qbcaGFC6XKAzFLtTibgo0r6Evn788u3ZiScuIXudGvIYO1MUUrmzJCQ53tn6YGlE2k7gey3WJjMBV9l04VMFnNq5XEQe2ckYICnZ72EZMYegvgAiyKFDzKSv2KY%2FgennvtTyc4d3cmxXfuQA6k8EOmOLj0i6VV31pZgDya2iWqUli7V18D0gt%2BiqYKMT2LffT3V83ExwT8BL4SxlSmsUxA0diEUvaDLjUEAeOJLyEG%2FF77RY9lwsoPGfUegfBb%2FNt8rM9Az6qwR%2FkqkrpvPTxHGFEbOSpaRN%2FwiTSCDdgGqWO9ydueuwqFZgO46JPJrr4byXLZeseXBFarAo9O2mHNk3syA%2BQk%2BzYTCG%2B17%2FQ5jeWLWEtg3NsRKeIZAtU5q2onCXHDMywdCinKdN8oven2gFm5pARD6LVSPk8UDX1vQKje21UqR0B3cVmpykkQwlBN7TjgHkZlNmwD6rrB%2BtvXPYZFNPFD2ljVeOsFvgMJ3Q%2B8wGOrEB8sKxYXxhskvwjH1dGOxfLztLc3I3gXWeVwdwUK6YbhjgVBpDMrWg3XTQDoMwRKlclO%2BgXl6QnIPg5RLtpPOQWN8SW4VFyMZ5vYsshGenMOKoXHkNdk3xcgh1AasKFXGrsV%2FqOD2QvLlxweT0TS9HeLV%2F8DecrCfy%2FR63MzBOJzX%2F3Is5SkhHk%2Fp2rK%2FqIq%2FTbdcZynEs9BVnjt4V6wVy2vlkyhl3otJSkz55vAzoKUAO&X-Amz-Signature=486abcc090b016d0eefcafbada52d474433a2cf2568b8f01563e381050faefe0&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 3.
Fig. 4.
![S. Distribution of potential energy of an electron in the cathodeanode region for an ideal converter (based on [12, 13])](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/694828ee7c29e05adc524c36/j_ama-2025-0072_fig_004.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKB6JPJ4IZ%2F20260225%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260225T161021Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEEQaDGV1LWNlbnRyYWwtMSJHMEUCIHhv10Z7nO7YqDTi8wtzJH7COmtSv%2BOAEgEKdAzIyfKEAiEA4mJK1%2F2voErlvET3qYn2JQZpjBGOZOKV5jybVBw8Iy4qvAUIDRACGgw5NjMxMzQyODk5NDAiDCk0eNQI0aH9UhOBUSqZBQccYCExbh8%2BahzenU72hQ7RE66Jh1KQow0a%2F78mVcc5Wa%2Bwiym3Hc33raHHKENgJYQQLZqTkoFa76X6ICDI3GledJGqHTGtQAwPxmY9OiJ%2BjaxgZhwEz%2BQyG4nvju3P2KIIbCATwQHGxk2Akqpx%2Bopzzkrdx7E4rQNDyC%2BWMuChoeMh7ufwDYKu8IdfVQP6PZIJg%2FvS7wlVM2o75HrdjkGc2tI6MEu1OZokHmjdlDi7PxBSd%2Fgi%2FeqLL28eu9hEWTVPAgS3StbFzEE0afO68MGcQfGwzhBXX6a%2BAUWPjPSyfvhgpOmH7D3LTiQWbQpiRoM10f6Vxc9ndLXupq6kzVGLYGL0s0gOHrwIN5A%2FBE3Jbl%2FCeL6B7HUylIvuc0myu88Sj8BNV9bzOtk2qbcaGFC6XKAzFLtTibgo0r6Evn788u3ZiScuIXudGvIYO1MUUrmzJCQ53tn6YGlE2k7gey3WJjMBV9l04VMFnNq5XEQe2ckYICnZ72EZMYegvgAiyKFDzKSv2KY%2FgennvtTyc4d3cmxXfuQA6k8EOmOLj0i6VV31pZgDya2iWqUli7V18D0gt%2BiqYKMT2LffT3V83ExwT8BL4SxlSmsUxA0diEUvaDLjUEAeOJLyEG%2FF77RY9lwsoPGfUegfBb%2FNt8rM9Az6qwR%2FkqkrpvPTxHGFEbOSpaRN%2FwiTSCDdgGqWO9ydueuwqFZgO46JPJrr4byXLZeseXBFarAo9O2mHNk3syA%2BQk%2BzYTCG%2B17%2FQ5jeWLWEtg3NsRKeIZAtU5q2onCXHDMywdCinKdN8oven2gFm5pARD6LVSPk8UDX1vQKje21UqR0B3cVmpykkQwlBN7TjgHkZlNmwD6rrB%2BtvXPYZFNPFD2ljVeOsFvgMJ3Q%2B8wGOrEB8sKxYXxhskvwjH1dGOxfLztLc3I3gXWeVwdwUK6YbhjgVBpDMrWg3XTQDoMwRKlclO%2BgXl6QnIPg5RLtpPOQWN8SW4VFyMZ5vYsshGenMOKoXHkNdk3xcgh1AasKFXGrsV%2FqOD2QvLlxweT0TS9HeLV%2F8DecrCfy%2FR63MzBOJzX%2F3Is5SkhHk%2Fp2rK%2FqIq%2FTbdcZynEs9BVnjt4V6wVy2vlkyhl3otJSkz55vAzoKUAO&X-Amz-Signature=4559c2100112d63cc3761f63d3d57dd783db388265e3a8b13d9c787b7789dfb1&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 5.
Fig. 6.
Fig. 7.
Fig. 8.
Fig. 9.
Fig. 10.
Fig. 11.
Fig. 12.
Fig. 13.
Fig. 14.
Fig. 15.
Fig. 16.
Fig. 17.
Fig. 18.
Temperature values of key converter components as a function of tungsten microheater temperature for design with molybdenum bases
| Theater [K] | 873.2 | 973.2 | 1073.2 | 1173.2 | 1273.2 | 1373.2 | 1473.2 | |
|---|---|---|---|---|---|---|---|---|
| Cathode | Taverage | 795.5 | 879.9 | 964.2 | 1048.6 | 1132.8 | 1217.0 | 1300.7 |
| Tmax | 873.2 | 973.2 | 1073.2 | 1173.2 | 1273.2 | 1373.2 | 1473.2 | |
| Tmin | 520.9 | 550.4 | 579.9 | 609.3 | 638.7 | 668.0 | 697.2 | |
| Cathode base | Taverage | 516.4 | 544.9 | 573.5 | 602.0 | 630.5 | 658.9 | 687.2 |
| Tmax | 649.4 | 704.5 | 759.6 | 814.5 | 869.4 | 924.2 | 978.6 | |
| Tmin | 450.6 | 466.1 | 481.5 | 497.0 | 512.4 | 527.8 | 543.1 | |
| Anode | Taverage | 397.9 | 432.1 | 468.8 | 507.7 | 548.6 | 590.8 | 633.6 |
| Tmax | 408.0 | 447.6 | 491.8 | 540.5 | 593.7 | 651.4 | 713.1 | |
| Tmin | 404.0 | 441.5 | 482.7 | 527.6 | 575.9 | 627.5 | 681.6 | |
| Anodebase | Taverage | 397.8 | 432.0 | 468.6 | 507.4 | 548.2 | 590.3 | 632.9 |
| Tmax | 400.1 | 435.5 | 473.8 | 514.9 | 558.5 | 604.0 | 650.9 | |
| Tmin | 396.7 | 430.3 | 466.1 | 503.8 | 543.3 | 583.7 | 624.3 | |
Temperature values of key converter components as a function of tungsten microheater temperature for design with copper bases
| Theater [K] | 873.2 | 973.2 | 1073.2 | 1173.2 | 1273.2 | 1373.2 | 1473.2 | |
|---|---|---|---|---|---|---|---|---|
| Cathode | Taverage | 779.4 | 860.6 | 941.8 | 1022.9 | 1104.0 | 1185.0 | 1266.0 |
| Tmax | 873.2 | 973.2 | 1073.2 | 1173.2 | 1273.2 | 1373.2 | 1473.2 | |
| Tmin | 509.1 | 536.3 | 563.5 | 590.6 | 617.7 | 644.7 | 671.7 | |
| Cathode base | Taverage | 509.1 | 536.2 | 563.3 | 590.4 | 617.5 | 644.5 | 671.5 |
| Tmax | 570.4 | 609.8 | 649.2 | 688.5 | 727.8 | 767.0 | 806.2 | |
| Tmin | 474.9 | 495.3 | 515.6 | 535.9 | 556.2 | 576.4 | 596.7 | |
| Anode | Taverage | 402.3 | 438.9 | 479.0 | 522.3 | 568.7 | 618.0 | 669.7 |
| Tmax | 406.3 | 445.1 | 488.0 | 535.2 | 586.6 | 642.0 | 701.4 | |
| Tmin | 397.4 | 431.3 | 467.7 | 506.2 | 546.5 | 588.2 | 630.5 | |
| Anode base | Taverage | 397.4 | 431.3 | 467.6 | 506.1 | 546.5 | 588.1 | 630.4 |
| Tmax | 398.2 | 432.5 | 469.5 | 508.8 | 550.1 | 593.0 | 636.9 | |
| Tmin | 396.9 | 430.6 | 466.6 | 504.7 | 544.4 | 585.3 | 626.9 | |
Thermal and physical properties of materials used in the model
| Material | Thermal Conductivity | Specific heat | Density | Emissivity |
|---|---|---|---|---|
| Stainless Steel 316L | 16.2 | 500.0 | 8000 | 0.28 |
| Molybdenum (Mo) | 138.0 | 250.0 | 10200 | 0.05 |
| Copper (Cu) | 398.0 | 385.0 | 8960 | 0.03 |
| Aluminum Oxide (Al2O3) | 30.0 | 880.0 | 3960 | 0.25 |
| Pyrex 7740 borosilicate glass | 1.14 | 830.0 | 2230 | 0.92 |
Temperature values of key converter components as a function of tungsten microheater temperature in a design with bases made of 316L steel
| Theater [K] | 873.2 | 973.2 | 1073.2 | 1173.2 | 1273.2 | 1373.2 | 1473.2 | |
|---|---|---|---|---|---|---|---|---|
| Cathode | Taverage | 839.7 | 932.8 | 1025.8 | 1118.7 | 1211.4 | 1304.0 | 1396.4 |
| Tmax | 873.2 | 973.2 | 1073.2 | 1173.2 | 1273.2 | 1373.2 | 1473.2 | |
| Tmin | 555.7 | 592.1 | 628.4 | 664.6 | 700.7 | 736.6 | 780.4 | |
| Cathode base | Taverage | 540.1 | 573.4 | 606.6 | 639.6 | 672.6 | 705.5 | 738.2 |
| Tmax | 817.3 | 905.7 | 993.8 | 1081.5 | 1169.0 | 1255.9 | 1359.1 | |
| Tmin | 393.4 | 397.5 | 401.6 | 405.8 | 409.9 | 414.0 | 417.8 | |
| Anode | Taverage | 420.3 | 465.9 | 517.9 | 576.2 | 640.0 | 709.3 | 783.6 |
| Tmax | 424.8 | 472.8 | 528.0 | 590.4 | 659.4 | 735.1 | 817.8 | |
| Tmin | 403.4 | 440.1 | 480.1 | 523.0 | 567.9 | 614.5 | 662.2 | |
| Anode base | Taverage | 402.2 | 438.2 | 477.4 | 519.3 | 562.9 | 607.9 | 653.8 |
| Tmax | 417.9 | 462.2 | 512.5 | 568.5 | 629.5 | 695.3 | 764.8 | |
| Tmin | 394.8 | 426.9 | 461.0 | 496.5 | 532.2 | 567.9 | 603.2 | |