Transient decay of beam-produced fields in thin-walled tubes

Ekdahl, Carl

doi:10.1063/1.1372368

Cited by 4 publications

(6 citation statements)

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“…(15) and (16) and yielding complex eigenvalues (c c r þ ix). The value of X now affects both c r as well as x, as shown in solutions for experimental parameters plotted in Fig.…”

Section: Effect Of Wall Rotationmentioning

confidence: 99%

“…1 in Eqs. (15) and (16), c ¼ f 2 s a a ; 2 s b a À iXg. The corresponding eigenfunctions are shown in Figs.…”

Section: Effect Of Wall Rotationmentioning

confidence: 99%

“…(15) and (16), limiting cases with respect to rotation (X) and mutual inductance (a) are treated separately.…”

Section: Vacuum Field Eigenmodes and Vertical Field Penetrationmentioning

confidence: 99%

“…12,13 EFs are also important to the accelerator community for related reasons. 14,15 Several studies have theoretically predicted that differential rotation of a conducting boundary can stabilize MHD modes. [16][17][18][19] As such, they have been considered for future devices.…”

Section: Introductionmentioning

confidence: 99%

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Asymmetric error field interaction with rotating conducting walls

et al. 2012

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The interaction of error fields with a system of differentially rotating conducting walls is studied analytically and compared to experimental data. Wall rotation causes eddy currents to persist indefinitely, attenuating and rotating the original error field. Superposition of error fields from external coils and plasma currents are found to break the symmetry in wall rotation direction. The vacuum and plasma eigenmodes are modified by wall rotation, with the error field penetration time decreased and the kink instability stabilized, respectively. Wall rotation is also predicted to reduce error field amplification by the marginally stable plasma.

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“…(15) and (16) and yielding complex eigenvalues (c c r þ ix). The value of X now affects both c r as well as x, as shown in solutions for experimental parameters plotted in Fig.…”

Section: Effect Of Wall Rotationmentioning

confidence: 99%

“…1 in Eqs. (15) and (16), c ¼ f 2 s a a ; 2 s b a À iXg. The corresponding eigenfunctions are shown in Figs.…”

Section: Effect Of Wall Rotationmentioning

confidence: 99%

“…(15) and (16), limiting cases with respect to rotation (X) and mutual inductance (a) are treated separately.…”

Section: Vacuum Field Eigenmodes and Vertical Field Penetrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Asymmetric error field interaction with rotating conducting walls

et al. 2012

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“…The resistive wall instability [22][23][24] is similar to the IDI in that it arises from the imbalance of forces from the image charge and image current. Where the IDI occurs in discontinuities, the resistive wall instability occurs in continuous parts of the accelerator and leads to an attractive force toward the beam pipe wall.…”

Section: Isolating the Idimentioning

confidence: 99%

Direct measurement of the image displacement instability in a linear induction accelerator

Burris-Mog

Ekdahl

Moir

2017

Phys. Rev. Accel. Beams

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The image displacement instability (IDI) has been measured on the 20 MeV Axis I of the dual axis radiographic hydrodynamic test facility and compared to theory. A 0.23 kA electron beam was accelerated across 64 gaps in a low solenoid focusing field, and the position of the beam centroid was measured to 34.3 meters downstream from the cathode. One beam dynamics code was used to model the IDI from first principles, while another code characterized the effects of the resistive wall instability and the beam breakup (BBU) instability. Although the BBU instability was not found to influence the IDI, it appears that the IDI influences the BBU. Because the BBU theory does not fully account for the dependence on beam position for coupling to cavity transverse magnetic modes, the effect of the IDI is missing from the BBU theory. This becomes of particular concern to users of linear induction accelerators operating in or near low magnetic guide fields tunes.

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Deconvolving long-pulse electron-beam centroid data from resistive wall-current monitors

Carlsten

2002

Review of Scientific Instruments

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A technique is described to deconvolve long-pulse electron-beam centroid data from resistive wall-current monitors. These monitors are typically capable of accurately measuring total current for tens of microseconds, but, due to magnetic diffusion, tend to give direct centroid measurements only up to hundreds of nanoseconds. As a result, resistive wall-current monitors are usually not considered reliable for long-pulse operation. However, the voltage signals azimuthally around the monitor still contains that information, and the information can be easily deconvolved by differentiating the signals. In this article, the diffusive part of Maxwell's equations is used to find an expression for the time response of a resistive wall-current monitor for a beam of arbitrary current and centroid evolution. A simple way of inverting this response is shown to find the beam centroid as a function of time within the electron pulse.

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Transient decay of beam-produced fields in thin-walled tubes

Cited by 4 publications

References 0 publications

Asymmetric error field interaction with rotating conducting walls

Asymmetric error field interaction with rotating conducting walls

Direct measurement of the image displacement instability in a linear induction accelerator

Deconvolving long-pulse electron-beam centroid data from resistive wall-current monitors

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