摘要:

Reported are measurements on the interaction between a relativistic electron beam (REB) with the parameters 800 kV, 6 kA, 50–150 nsec, and a plasma with a density ofne=1.0×1019m−3–1.0×1020m−3. The electron temperature during and after the beam pulse is obtained by means of Thomson scattering. Also measured is the angular distribution of the beam electrons as a function of time and position. By varying the angular spread of the beam it is possible to pass from a kinetic to a quasihydrodynamic interaction. In both regimes measurements are compared with the appropriate theoretical model. Energy transfer is largest in the quasihydrodynamic regime and amounts to 2.5×103J/m3or 2.2×1016eV/cm3. The electron temperature reaches values of 150 eV and appears limited by the electron heat conduction along the magnetic field.

ISSN:0031-9171    

DOI:10.1063/1.864648

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Reported are measurements on the high‐frequency fields generated by a relativistic electron beam plasma interaction in the BP II experiment. Measurements are done at fixed positions as well as integrated over the length of the experiment. At fixed positions time‐resolved spectroscopy on hydrogen and helium lines is applied. The integrated measurements are performed with a magnetic energy analyzer, which measures the energy distribution of the relativistic electron beam at the end of the experiment. Spectroscopic measurements of the dynamic Stark effect and forbidden transitions lead to hf fields with amplitudes in the order of 1 MV/m. The interpretation of the beam energy spectra suggests localized fields with field strengths as great as 108V/m.

ISSN:0031-9171    

DOI:10.1063/1.864649

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Frequency‐resolved measurements of radiation growth have been performed on a millimeter‐wave free‐electron laser using an intense relativistic electron beam. These measurements have shown large radiation growth rates (approximately 2 dB/cm) over a broad instantaneous bandwidth (66–90 GHz), in good agreement with predictions of theory for operation in the collective regime. Growth narrowing and saturation effects have also been observed. In addition, a large increase in experimental power and efficiency has been observed to result from tapering the strength of the axial magnetic field in the sense that compensates for kinetic energy extraction from the electron beam. Direct calorimetric measurements indicate the production of ≳75 MW centered at 75 GHz with 6% experimental efficiency.

ISSN:0031-9171    

DOI:10.1063/1.864650

出版商:AIP    

年代:1984

数据来源: AIP