Deflection Of Carbon Dioxide Laser And Helium-neon Laser Beams In A Long-pulse Relativistic Electron Beam Diode

Deflection of carbon dioxide and helium-neon laser beams has been used to measure plasma and neutral density gradients during the operating mode and after the shorting time of a long-pulse field-emission electron beam diode. The neutral density gradient was less than 1 x 10
¹⁸
cm
^-
-4 during the electron beam pulse. Upon diode-shorting, neutral density gradients increased to (10
¹⁸
-10
¹⁹
) cm
^-4
over ˜1 μs, and decayed over many microseconds. Plasma density gradients of (10
¹⁴
-10
¹⁵
) cm
^-4
were observed throughout the diode during the final microsecond of the 2-3 μs electron beam pulse. Plasma density gradients of ˜10
¹⁵
cm
^-4
were also observed after shorting. These experiments demonstrate the value of helium-neon and carbon-dioxide laser deflection for diagnosing neutral particles and plasma in long-pulse electron beam diodes.