High-power coaxial ubitron oscillator: theory and design

Balkcum, Adam; McDermott, D.B.; Phillips, R.; Luhmann, Neville C.

doi:10.1109/27.700790

Cited by 20 publications

(9 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1, the Green's function which satisfies the conditions in (6a) and (6b) is given by (8), shown at the bottom of the page, where…”

Section: Center-of-mass Force In a Coaxial Conducting Structurementioning

confidence: 99%

“…In particular, we compare the spacecharge limits of a ring of charge (zero radial thickness and zero longitudinal thickness) with radius r b , i.e., g(r, z) = δ(r − r b )δ(z)/2πr b with the space-charge limits of a zeroradial-thickness annular beam of radius r b and a Gaussian longitudinal distribution with a root-mean-square (rms) bunch length σ z measured in the beam rest frame, i.e., g(r, [8]. Since the beam radius must lie in the range of r i ≤ r b ≤ r o , the horizontal axis of Fig.…”

Section: Evaluation Of Space-charge Limitmentioning

confidence: 99%

“…In Section III, we introduce a Hamiltonian procedure to derive the equations of motion for the center-of-mass, which includes the effects of the off-axis force and an external magneticfocusing field. From the equation of motion, we derive the space-charge limit and show its relevance for the design of the UC Davis/SLAC 2.8-GHz ubitron oscillator [8]. In Section IV, we include a summary of our results.…”

Section: Introductionmentioning

confidence: 97%

“…Finally, we will show how the space-charge limit is applicable to the design of the UC Davis/SLAC 2.8-GHz ubitron oscillator [8].…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, magnetic fields due to permanent magnets are not always strong enough to prevent the center-of-mass instability, and a careful analysis of the offaxis instability should be carried out to determine if the PPMfocusing strength is adequate for the beam-current design. A design study for the 1-GW University of California, Davis (UC Davis)/Stanford Linear Accelerator Center (SLAC) 2.8-GHz ubitron oscillator [8] was conducted which utilized a 9.6-kA bunched annular electron beam in a coaxial conducting structure along with a PPM-focusing scheme having a maximum field of 330 G. The study used 2 1/2-D particle-in-cell simulations to demonstrate both the device's capabilities, as well as the effectiveness of the PPM focusing for propagating the beam. While 2 1/2-D simulations are very effective for analyzing any beam dynamics and electromagnetic-mode interactions which are circularly symmetric, these simulations are not able to resolve the physics of the center-of-mass force which is an off-axis fully 3-D effect.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Off-Axis Space-Charge Limit for a Bunched Electron Beam in a Coaxial Conducting Structure

Hess

2008

IEEE Trans. Plasma Sci.

View full text Add to dashboard Cite

We derive a space-charge limit for a circularly symmetric bunched electron beam that has its center-of-mass slightly offset from the axis of a circularly symmetric coaxial conducting structure. The limit is a necessary condition for beam stability resulting from the following two forces acting on the center-ofmass of the electron bunch: 1) the radial deflecting force due to the induced surface charges and currents on the conducting structure and 2) the confining force due to the presence of an external solenoidal magnetic-focusing field. We show explicit calculations of the space-charge limits for beam-charge distributions, which in the radial direction have zero thickness, i.e., thin annular beams, and in the axial direction have either zero longitudinal thickness or Gaussian like distributions. Finally, we show how this limit is applicable to a previous design study of the University of California, Davis/Stanford Linear Accelerator Center 2.8-GHz coaxial ubitron oscillator.Index Terms-Electron beam, high-power microwave source.

show abstract

“…1, the Green's function which satisfies the conditions in (6a) and (6b) is given by (8), shown at the bottom of the page, where…”

Section: Center-of-mass Force In a Coaxial Conducting Structurementioning

confidence: 99%

Section: Evaluation Of Space-charge Limitmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

“…Finally, we will show how the space-charge limit is applicable to the design of the UC Davis/SLAC 2.8-GHz ubitron oscillator [8].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning