Suppression of Circularly Polarized Microwave Dielectric Multipactor by Normal Gyromagnetic Field

This article shows that multipactor on a dielectric window exposed to circularly polarized microwave can be suppressed by a proper normal gyromagnetic field, while a normal gyromagnetic field is traditionally considered to strengthen multipactor in a linearly polarized wave. The dc electric field and the deposited power of multipactor in circularly polarized microwave with normal gyromagnetic field are predicted theoretically and validated by particle-in-cell simulations. The results show that the multipactor threshold
${E}_{{0}}$
is about
$\pi \vert \omega +\omega _{c} \vert ({m}\varepsilon _{\text {low}}/{(}{8}{e}^{{2}}{)})^{1/2} $
for left-handed circularly polarized waves or
$\pi \vert \omega -\omega _{c} \vert ({m}\varepsilon _{\text {low}}/{(}{8}{e}^{{2}}{)})^{1/2} $
for right-handed circularly polarized waves, where
${E}_{{0}}$
is the amplitude of RF electric field,
$\omega $
is the angular frequency of RF electric field,
$\omega _{c}$
is the cyclotron angular frequency due to the normal magnetic field
${B}$
(
$\omega _{c} > 0$
if
${B}$
is pointing to the surface, while
$\omega _{c} < 0$
if
${B}$
is away from the surface),
${m}$
is the electron mass,
${e}$
is the element charge, and
$\varepsilon _{\text {low}}$
is the first crossover energy in the unit of secondary electron yield.