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=ASIA6AP2G7AKHOSRDSYN%2F20251221%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251221T232347Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEBoaDGV1LWNlbnRyYWwtMSJGMEQCIBJrAYNgXa0TszaFPyjBdrmbqqwTbPBJcLzR70eUm5qUAiBW%2BrxrJwNeiR3Ftcd0SEFgcv80x4%2Bl7djiHoQJLOrogirEBQjj%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F8BEAIaDDk2MzEzNDI4OTk0MCIMOX4wF%2FDC4s5HS0VaKpgFm14XBePPZB4vVKWuFQteVKqhsT4O06pfK%2B6v2YRYQZ3PA7mkdLZX%2FD3zegleJnvVxbpxOkrnk0dqUJhn4C4Y3%2Fk%2Bh4gIMTS%2Byse91rafH9nvQUZmiAm7Q0IVHlTN3L%2FpzBeSo7DXGNM7eBv8z322sf%2F4I7cT7jeoOeVAqbcowljETlhG16CC%2B90IMl6MbcV76zgmd82o9iO4A0sSLvSfvyEcqh6HGUvkM0W4gkv1e8GTiSXWzXvoxqpPOwib1sL6SP4GjKdThz9z%2FdXFIcyqQn7rRuTAzmbI9FE3hbqLRxxO5fHPRHsdrFI46W%2BQXy0ghw0miVDQcw820oOd5LkIP5Lq6eB7XG6Ee9Rb%2FKvkCnqUMEXwT70lvKThKeq55Ah0KN2bvte8DII9fnz8bG3X%2FNwjbJ54Eedwj970ECryXYx0c7%2BRJSd0vM%2B%2BOZQpY1MWgBGPRLMcgGKWbT9%2FqHfDn37xyBTzyvfGsULzLSjKd19ATQxCywAjPuYWyQfz3KUvz4%2F2qE17K4GKc93fFdZmH6tEo3c8W%2FmwUfQ%2FVpE6CpvBECeW6Ib8HNUCAxWjwtGO2X7YA7rUU9TayJG2NQUw%2Bxu2H3fIcqGRf9je1%2FZjdXmLcKqT820X5LRGu%2B%2FMhdwga1AFL2xXuLcmQ80iGHq8OChEqn3CvIYQ4wZ%2FJvjC1WWgHComwrUWzZl6SfMV7aoHJ6H3ZYNsLzY%2B3fDKFcU6Tn33q115YUo%2Faugp4wx16x90y1eM9r80nnRFX9x2LK23Dzd3NDiolGLXAlND0OaFkuqqg4zkbWG5o36ONBedkoc%2FLPrfP7iZACA8NajlKl%2FJ12YnAjJyCBVVVfAVVXjvA%2F7RBmQD%2Fz5BctsYuAUHuusxUtgjR0NYMTCN6qDKBjqyAVFJNlsndigDgxVQGWhMNFuShqsXGjhAWqa9j0B2S6OmzvcmnZexdbr28%2Fe6AdLWEJmmBLtNemmXTC1ESONFTia3mUOpq9CXwrqLzD1vNt1zgleTqDLB8gcRhG20tW7uZAG2acXZnZajextDNZ4jmrG6T3zPa0T1JFKaiKd8VNR6shHWINNBQiQNY1YCgJQGmUTzbr0vob%2FrFLzaXlC8cijOep1GkMSzOQxEZxvKNCRZ3ug%3D&X-Amz-Signature=a30fb6273b4a81045410c6c2c761811dfa98dc8210b4cecfc9f911b117e47a24&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=ASIA6AP2G7AKHOSRDSYN%2F20251221%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251221T232347Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEBoaDGV1LWNlbnRyYWwtMSJGMEQCIBJrAYNgXa0TszaFPyjBdrmbqqwTbPBJcLzR70eUm5qUAiBW%2BrxrJwNeiR3Ftcd0SEFgcv80x4%2Bl7djiHoQJLOrogirEBQjj%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F8BEAIaDDk2MzEzNDI4OTk0MCIMOX4wF%2FDC4s5HS0VaKpgFm14XBePPZB4vVKWuFQteVKqhsT4O06pfK%2B6v2YRYQZ3PA7mkdLZX%2FD3zegleJnvVxbpxOkrnk0dqUJhn4C4Y3%2Fk%2Bh4gIMTS%2Byse91rafH9nvQUZmiAm7Q0IVHlTN3L%2FpzBeSo7DXGNM7eBv8z322sf%2F4I7cT7jeoOeVAqbcowljETlhG16CC%2B90IMl6MbcV76zgmd82o9iO4A0sSLvSfvyEcqh6HGUvkM0W4gkv1e8GTiSXWzXvoxqpPOwib1sL6SP4GjKdThz9z%2FdXFIcyqQn7rRuTAzmbI9FE3hbqLRxxO5fHPRHsdrFI46W%2BQXy0ghw0miVDQcw820oOd5LkIP5Lq6eB7XG6Ee9Rb%2FKvkCnqUMEXwT70lvKThKeq55Ah0KN2bvte8DII9fnz8bG3X%2FNwjbJ54Eedwj970ECryXYx0c7%2BRJSd0vM%2B%2BOZQpY1MWgBGPRLMcgGKWbT9%2FqHfDn37xyBTzyvfGsULzLSjKd19ATQxCywAjPuYWyQfz3KUvz4%2F2qE17K4GKc93fFdZmH6tEo3c8W%2FmwUfQ%2FVpE6CpvBECeW6Ib8HNUCAxWjwtGO2X7YA7rUU9TayJG2NQUw%2Bxu2H3fIcqGRf9je1%2FZjdXmLcKqT820X5LRGu%2B%2FMhdwga1AFL2xXuLcmQ80iGHq8OChEqn3CvIYQ4wZ%2FJvjC1WWgHComwrUWzZl6SfMV7aoHJ6H3ZYNsLzY%2B3fDKFcU6Tn33q115YUo%2Faugp4wx16x90y1eM9r80nnRFX9x2LK23Dzd3NDiolGLXAlND0OaFkuqqg4zkbWG5o36ONBedkoc%2FLPrfP7iZACA8NajlKl%2FJ12YnAjJyCBVVVfAVVXjvA%2F7RBmQD%2Fz5BctsYuAUHuusxUtgjR0NYMTCN6qDKBjqyAVFJNlsndigDgxVQGWhMNFuShqsXGjhAWqa9j0B2S6OmzvcmnZexdbr28%2Fe6AdLWEJmmBLtNemmXTC1ESONFTia3mUOpq9CXwrqLzD1vNt1zgleTqDLB8gcRhG20tW7uZAG2acXZnZajextDNZ4jmrG6T3zPa0T1JFKaiKd8VNR6shHWINNBQiQNY1YCgJQGmUTzbr0vob%2FrFLzaXlC8cijOep1GkMSzOQxEZxvKNCRZ3ug%3D&X-Amz-Signature=16f2ab10d768b69d2369efb4e676638c8bc00e2d839e13488752bb6e6236adc6&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=ASIA6AP2G7AKHOSRDSYN%2F20251221%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251221T232347Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEBoaDGV1LWNlbnRyYWwtMSJGMEQCIBJrAYNgXa0TszaFPyjBdrmbqqwTbPBJcLzR70eUm5qUAiBW%2BrxrJwNeiR3Ftcd0SEFgcv80x4%2Bl7djiHoQJLOrogirEBQjj%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F8BEAIaDDk2MzEzNDI4OTk0MCIMOX4wF%2FDC4s5HS0VaKpgFm14XBePPZB4vVKWuFQteVKqhsT4O06pfK%2B6v2YRYQZ3PA7mkdLZX%2FD3zegleJnvVxbpxOkrnk0dqUJhn4C4Y3%2Fk%2Bh4gIMTS%2Byse91rafH9nvQUZmiAm7Q0IVHlTN3L%2FpzBeSo7DXGNM7eBv8z322sf%2F4I7cT7jeoOeVAqbcowljETlhG16CC%2B90IMl6MbcV76zgmd82o9iO4A0sSLvSfvyEcqh6HGUvkM0W4gkv1e8GTiSXWzXvoxqpPOwib1sL6SP4GjKdThz9z%2FdXFIcyqQn7rRuTAzmbI9FE3hbqLRxxO5fHPRHsdrFI46W%2BQXy0ghw0miVDQcw820oOd5LkIP5Lq6eB7XG6Ee9Rb%2FKvkCnqUMEXwT70lvKThKeq55Ah0KN2bvte8DII9fnz8bG3X%2FNwjbJ54Eedwj970ECryXYx0c7%2BRJSd0vM%2B%2BOZQpY1MWgBGPRLMcgGKWbT9%2FqHfDn37xyBTzyvfGsULzLSjKd19ATQxCywAjPuYWyQfz3KUvz4%2F2qE17K4GKc93fFdZmH6tEo3c8W%2FmwUfQ%2FVpE6CpvBECeW6Ib8HNUCAxWjwtGO2X7YA7rUU9TayJG2NQUw%2Bxu2H3fIcqGRf9je1%2FZjdXmLcKqT820X5LRGu%2B%2FMhdwga1AFL2xXuLcmQ80iGHq8OChEqn3CvIYQ4wZ%2FJvjC1WWgHComwrUWzZl6SfMV7aoHJ6H3ZYNsLzY%2B3fDKFcU6Tn33q115YUo%2Faugp4wx16x90y1eM9r80nnRFX9x2LK23Dzd3NDiolGLXAlND0OaFkuqqg4zkbWG5o36ONBedkoc%2FLPrfP7iZACA8NajlKl%2FJ12YnAjJyCBVVVfAVVXjvA%2F7RBmQD%2Fz5BctsYuAUHuusxUtgjR0NYMTCN6qDKBjqyAVFJNlsndigDgxVQGWhMNFuShqsXGjhAWqa9j0B2S6OmzvcmnZexdbr28%2Fe6AdLWEJmmBLtNemmXTC1ESONFTia3mUOpq9CXwrqLzD1vNt1zgleTqDLB8gcRhG20tW7uZAG2acXZnZajextDNZ4jmrG6T3zPa0T1JFKaiKd8VNR6shHWINNBQiQNY1YCgJQGmUTzbr0vob%2FrFLzaXlC8cijOep1GkMSzOQxEZxvKNCRZ3ug%3D&X-Amz-Signature=d60e52d478301c3e7f5d7505aa09b8ef6548348db5416c6ab085e466874dd49f&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 | |