Operating point of long magnetically insulated vacuum transmission lines

Wang, Ming Y.; Capua, Marco S. Di

doi:10.1063/1.327576

Cited by 21 publications

(12 citation statements)

References 5 publications

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“…Notice that the lines both run near I min (minimum I a for constant V) and then, as the load impedance drops, the data fall towards I a = I c . It is likely that the line is actually operating at the minimum energy condition which is experimentally indistinguishable from the minimum total current (Wang & Di Capua 1980). The observed tendency of the line to operate at minimum current is an extremely useful fact of magnetically insulated transmission line behavior.…”

Section: Line Voltage From I a And I Cmentioning

confidence: 92%

A simple theory of magnetic insulation from basic physical considerations

1983

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Section: Line Voltage From I a And I Cmentioning

confidence: 92%

A simple theory of magnetic insulation from basic physical considerations

1983

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“…Consequently, the comparisons in Table II between the self-limited-MITL results and corresponding predictions are valid only to the extent that the minimum-current assumption is valid. (Some authors have speculated that a self-limited MITL operates not at the minimum anode current, but instead at the current that is obtained in a minimum-energy calculation [12,20]. We discuss such a calculation in Appendix A.…”

Section: Comparison Of the Collisional And Collisionless Models mentioning

confidence: 99%

“…6 of Ref. [20], Wang and Di Capua plot the ratio of the MITL anode current to the cathode current obtained in a variety of experiments and numerical simulations. (We caution that many of the reference numbers given in the caption of this figure are incorrect.)…”

Section: Observations That Suggest Effective Collisions Play a Non-nementioning

confidence: 99%

“…Several workers have speculated that a self-limited MITL may operate not at I a;min , but instead at the anode current that is obtained when a nominal value of the total MITL energy per unit length W is minimized [12,20]. This energy is assumed to be the sum of the following components: the energy of the steady-state electric field, the steady-state magnetic field, and the laminar component of the flow-electron velocities.…”

Section: Appendix A: Minimum-energy Operating Pointmentioning

confidence: 99%

“…We follow this convention herein, and assume that a self-limited MITL operates at I a;min . Several workers have speculated that the self-limited anode current may instead be that which is obtained by a minimum-energy calculation [12,20]. We discuss such a calculation in Appendix A.…”

Section: Introductionmentioning

confidence: 99%

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Analytic model of a magnetically insulated transmission line with collisional flow electrons

Stygar

Wagoner

Ives³

et al. 2006

Phys. Rev. ST Accel. Beams

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We have developed a relativistic-fluid model of the flow-electron plasma in a steady-state onedimensional magnetically insulated transmission line (MITL). The model assumes that the electrons are collisional and, as a result, drift toward the anode. The model predicts that in the limit of fully developed collisional flow, the relation between the voltage V a , anode current I a , cathode current I k , and geometric impedance Z 0 of a 1D planar MITL can be expressed as V a I a Z 0 h, where h 1=4 ÿ 1 1=2 ÿ lnb 2 ÿ 1 1=2 c=2 ÿ 1 and I a =I k . The relation is valid when V a * 1 MV. In the minimally insulated limit, the anode current I a;min 1:78V a =Z 0 , the electron-flow current I f;min 1:25V a =Z 0 , and the flow impedance Z f;min 0:588Z 0 . {The electronflow current I f I a ÿ I k . Following Mendel and Rosenthal [Phys. Plasmas 2, 1332 (1995)], we define the flow impedance Z f as V a =I 2 a ÿ I 2 k 1=2 .g In the well-insulated limit (i.e., when I a I a;min ), the electron-flow current I f 9V 2 a =8I a Z 2 0 and the flow impedance Z f 2Z 0 =3. Similar results are obtained for a 1D collisional MITL with coaxial cylindrical electrodes, when the inner conductor is at a negative potential with respect to the outer, and Z 0 & 40 . We compare the predictions of the collisional model to those of several MITL models that assume the flow electrons are collisionless. We find that at given values of V a and Z 0 , collisions can significantly increase both I a;min and I f;min above the values predicted by the collisionless models, and decrease Z f;min . When I a I a;min , we find that, at given values of V a , Z 0 , and I a , collisions can significantly increase I f and decrease Z f . Since the steady-state collisional model is valid only when the drift of electrons toward the anode has had sufficient time to establish fully developed collisional flow, and collisionless models assume there is no net electron drift toward the anode, we expect these two types of models to provide theoretical bounds on I a , I f , and Z f .

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