Beam stability and current loss in magnetic insulation

Bergeron, K.D.; Poukey, J. W.

doi:10.1063/1.325578

Cited by 9 publications

(7 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effective collision frequency due to plasma collective effects [16,21,22,24,28,29,33, may be orders of magnitude greater than the two-body collision frequency estimated above. To calculate the effective collision frequency would require modeling the nonlinear evolution of flow-electron-plasma instabilities until they achieve a turbulent steady state [53].…”

Section: Scaling Of the Effective Collision Frequencymentioning

confidence: 85%

“…However, as discussed in Sec. II B, a number of observations suggest that instabilities in the MITL's flow-electron plasma can result in electrostatic-and electromagnetic-field fluctuations, and that these can subject the electrons to effective collisions [16,21,22,24,28,29,33,. These observations imply that the frequency of such collisions can be sufficiently high to cause the flow electrons to have a small, but non-negligible, component of their drift velocities directed toward the anode.…”

Section: Introductionmentioning

confidence: 92%

“…(ix) In Ref. [16], Bergeron and Poukey describe several 2D numerical simulations of a MITL. They find that, when a parapotential force-balanced electron sheath is launched at the input to the MITL, the sheath ''does not propagate more than a short distance before being totally disrupted, apparently by beam instability.''…”

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

confidence: 99%

“…Other calculations that examine the stability of a MITL's electron sheath to various perturbations are presented in Refs. [16,24,29,33,49,51,52,55,56,63,64].…”

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

confidence: 99%

“…The other particles in the gap include electrons, ions, and neutrals from the residual gas in the gap due to the necessarily imperfect vacuum, and ions and neutrals that evolve from anode-and cathode-electrode plasmas into the gap during the power pulse. Effective collisions occur between the flow electrons and electrostatic-and electromagnetic-field fluctuations [16,21,22,24,28,29,33,.…”

Section: Two-body-particle and Effective Collisionsmentioning

confidence: 99%

See 4 more Smart Citations

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

Stygar

Wagoner

Ives³

et al. 2006

Phys. Rev. ST Accel. Beams

View full text Add to dashboard Cite

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 .

show abstract

Section: Scaling Of the Effective Collision Frequencymentioning

confidence: 85%

Section: Introductionmentioning

confidence: 92%

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

confidence: 99%

“…Other calculations that examine the stability of a MITL's electron sheath to various perturbations are presented in Refs. [16,24,29,33,49,51,52,55,56,63,64].…”

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

confidence: 99%

Section: Two-body-particle and Effective Collisionsmentioning

confidence: 99%

See 3 more Smart Citations

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

Stygar

Wagoner

Ives³

et al. 2006

Phys. Rev. ST Accel. Beams

View full text Add to dashboard Cite

show abstract

Self-magnetically insulated electron flow in vacuum transmission lines

et al. 1981

View full text Add to dashboard Cite

Theory of magnetically insulated electron flows in coaxial pulsed power transmission lines

Lawconnell

Neri

1990

Physics of Fluids B: Plasma Physics

View full text Add to dashboard Cite

The Cartesian magnetically insulated transmission line (MITL) theory of Mendel et al. [Appl. Phys. 50, 3830 (1979); Phys. Fluids 26, 3628 (1983)] is extended to cylindrical coordinates. A set of equations that describe arbitrary electron flows in cylindrical coordinates is presented. These equations are used to derive a general theory for laminar magnetically insulated electron flows. The laminar theory allows one to specify the potentials, fields, and densities across a coaxial line undergoing explosive electron emission at the cathode. The theory is different from others available in cylindrical coordinates in that the canonical momentum and total energy for each electron may be nonzero across the electron sheath. A nonzero canonical momentum and total energy for the electrons in the sheath allows the model to produce one-dimensional flows that resemble flows from lines with impedance mismatches and perturbing structures. The laminar theory is used to derive two new self-consistent cylindrical flow solutions: (1) for a constant density profile and (2) for a quadratic density profile of the form ρ=ρc[(r2m−r2)/(r2m−r2c)]. This profile is of interest in that it is similar to profiles observed in a long MITL simulation [Appl. Phys. 50, 4996 (1979)]. The theoretical flows are compared to numerical results obtained with two-dimensional (2-D) electromagnetic particle-in-cell (PIC) codes.

show abstract

Beam stability and current loss in magnetic insulation

Cited by 9 publications

References 4 publications

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

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

Self-magnetically insulated electron flow in vacuum transmission lines

Theory of magnetically insulated electron flows in coaxial pulsed power transmission lines

Contact Info

Product

Resources

About