Effect of convective loss on the parametric decay of cold electron plasma waves

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Abstract
The resonant decay of cold electron plasma waves was investigated in the Princeton L‐3 device in an argon plasma with n∼1010–1011 cm−3, B∼700 G–2 kG, f0∼50–80 MHz (ω0⩾10 ωlh). The decay waves were identified to be ion‐acoustic waves and cold electron plasma waves. Because of convective losses in the finite extent pump field, the threshold for parametric decay is considerably higher than the collisional threshold for the dominant E0⊥×B coupling. Coupling due to E0∥ can be important in low density, high magnetic field plasmas. At high densities (n≳3×1010 cm−3), E0⊥×B coupling becomes dominant. The E0⊥×B decay convective threshold was measured at various antenna lengths, magnetic field strengths, and plasma densities. The experimental results are in good agreement with theory. Indication of pump depletion and enchanced Landau heating of electrons were observed in the parametric decay process.