Beam Line Design, Beam Alignment Procedure, and Initial Results for the$W$-Band Gain Experiment at Los Alamos

A one-dimensional Vlasov-Poisson model for sheet beams is reviewed and extended to provide a simple framework for analysis of space-charge effects. Centroid and rms envelope equations including imagecharge effects are derived and reasonable parameter equivalences with commonly employed 2D transverse models of unbunched beams are established. This sheet-beam model is then applied to analyze several problems of fundamental interest. A sheet-beam thermal equilibrium distribution in a continuous focusing channel is constructed and shown to have analogous properties to two-and three-dimensional thermal equilibrium models in terms of the equilibrium structure and Debye screening properties. The simpler formulation for sheet beams is exploited to explicitly calculate the distribution of particle oscillation frequencies within a thermal equilibrium beam. It is shown that as space-charge intensity increases, the frequency distribution becomes broad, suggesting that beams with strong space-charge can have improved stability relative to beams with weak space-charge.

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“…(5) and (6) (4) and the finite geometry solution (10) for À@=@x, we can resolve the field of the finite geometry system as…”

Section: Sheet-beam Modelmentioning

confidence: 99%

“…One-dimensional (1D) sheet-beam models have been applied in the analysis of microwave devices and free-electron lasers [1][2][3][4][5]. 1D sheet-beam models have also been exploited as a simplified framework to gain insight into higher-dimensional models of beams in particle accelerators-particularly on difficult spacecharge effects.…”

Section: Introductionmentioning

confidence: 99%

Sheet beam model for intense space charge: Application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam

Lund

Friedman

Bazouin

2011

Phys. Rev. ST Accel. Beams

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“…The measured losses of about 10 dB were mostly due to the connection hardware and not the omniguide structure itself. In Figure 3 the transmission through the LANL's vaneloaded TWT structure [3] is shown for comparison, with a grey line. It can be easily seen from the figure that the vane-loaded structure has much smaller bandwidth (around 7 per cent) and higher losses (more than 20 dB).…”

Section: Figurementioning

confidence: 99%

“…The structure will be installed inside of a solenoid in our mm-wave electron beam test stand [3], which employs a 20-A, 120-kV electron beam. The structure will be driven from 90 to 100 GHz, and the gain (at low power) will be measured with available diagnostics to verify the interaction concept.…”

Section: Conclusion and Plansmentioning

confidence: 99%

“…A wide-band mmwave traveling-wave tube (TWT) amplifier development is underway at Los Alamos National Laboratory. We have constructed a 95 GHz TWT using a vane-loaded waveguide as a slow-wave structure and demonstrated a 7% bandwidth in a cold test [3]. Although promising, this approach leads to significant engineering and fabrication challenges.…”

Section: Introductionmentioning

confidence: 99%

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Progress on fabrication and testing of the omniguide traveling-wave tube structures

Смирнова

Carlsten

Earley

2008

2008 IEEE International Vacuum Electronics Conference

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Design of Sheet-Beam Electron Gun with Planar Cathode for Terahertz Devices

Srivastava

Wang

et al. 2009

J Infrared Milli Terahz Waves

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The design of a sheet-beam electron gun with planar cathode was made with the help of a three-dimensional electrostatic field solver that was capable of forming a sheet-beam of 19 mA at 12 kV. It uses one-dimensional three-fold beam cross-sectional area compression meets the specific requirement of a beam to be formed of height 30 µm and width 600 µm at the beam-waist position with over 100 A/cm 2 uniform current density and 0.068 π-mm-mrad emittance, typically, for 0.5 THz devices. A novel beam focusing electrode (BFE) provided with extended-corner rectangular-aperture geometry alleviating the commonly encountered sheet-beam formation problem with a gun that uses a conventional BFE, as well as it reduced beam emittance more than 50%. The practicability of the design was tested by the highvoltage, the thermal and structural analyses. Work has been initiated to test the performance of special high current scandate cathode using anode-aperture mapping.

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Beam Line Design, Beam Alignment Procedure, and Initial Results for the$W$-Band Gain Experiment at Los Alamos

Cited by 22 publications

References 7 publications

Sheet beam model for intense space charge: Application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam

Sheet beam model for intense space charge: Application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam

Progress on fabrication and testing of the omniguide traveling-wave tube structures

Design of Sheet-Beam Electron Gun with Planar Cathode for Terahertz Devices

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