Self-magnetic insulation in vacuum for coaxial geometry

Shope, S.L.; Poukey, J. W.; Bergeron, K.D.; McDaniel, D. H.; Toepfer, A.J.; VanDevender, J. Pace

doi:10.1063/1.325419

Cited by 32 publications

(7 citation statements)

References 7 publications

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“…4(b) of Ref. [15]. This impedance is 12%-23% less than the values 0:73Z 0 -0:83Z 0 predicted over this voltage range by the collisionless parapotential MITL model [8,9].…”

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

confidence: 43%

“…(vii) Measurements by Shope and colleagues [15] on a 1.37-m-long MITL powered by the HERMES-II accelerator show that for peak voltages between 3.5 and 10 MV, the self-limited MITL impedance is 0:64Z 0 , as indicated by Fig. 4(b) of Ref.…”

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

confidence: 96%

“…[Please see Fig. 4(a) of [15]. This figure actually plots the ratio V a =I a;min Z 0 as a function of V a .]…”

Section: Comparison Of the Collisional And Collisionless Models mentioning

confidence: 97%

“…Shope and colleagues [15] describe measurements performed on a 0.5-m-long coaxial MITL with Z 0 11 and a 1.3-cm AK gap. When V a is 1.3 MV, the measured value of I a;min Z 0 =V a is 1:9.…”

Section: Comparison Of the Collisional And Collisionless Models mentioning

confidence: 99%

“…Assuming this plasma expands at 2 cm=s, and that it is a perfect conductor, we find that the plasma does not significantly affect the results presented in Table II, due to the large gaps and short pulse lengths of the experiments. The most significant correction would be to the 1.3-MV measurements reported by Shope and colleagues [15], since these were performed with a 1.3-cm AK gap. Assuming that the cathode plasma had expanded for 40 ns by the time these measurements were made, the MITL impedance Z 0 would have been reduced from 10.94 to 10:21 , which would have reduced the measured value of I a;min Z 0 =V a from 1.9 to 1.77.…”

Section: Comparison Of the Collisional And Collisionless Models mentioning

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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“…4(b) of Ref. [15]. This impedance is 12%-23% less than the values 0:73Z 0 -0:83Z 0 predicted over this voltage range by the collisionless parapotential MITL model [8,9].…”

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

confidence: 43%

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

confidence: 96%

“…[Please see Fig. 4(a) of [15]. This figure actually plots the ratio V a =I a;min Z 0 as a function of V a .]…”

Section: Comparison Of the Collisional And Collisionless Models mentioning

confidence: 97%

“…Shope and colleagues [15] describe measurements performed on a 0.5-m-long coaxial MITL with Z 0 11 and a 1.3-cm AK gap. When V a is 1.3 MV, the measured value of I a;min Z 0 =V a is 1:9.…”

Section: Comparison Of the Collisional And Collisionless Models mentioning

confidence: 99%

Section: Comparison Of the Collisional And Collisionless Models mentioning

confidence: 99%

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