Generation of cherenkov superradiant pulses with correlated phases defined by sharp edges of high-current electron bunches
Recently coherent summation of several SR pulses generated in parallel channels has been demonstrated in X- and Ka wavelength bands. This possibility is caused by picosecond stability of explosive emission from a cold cathode and strong correlation of phase of the SR pulses with respect to the leading edge of the electron bunch. In fact stimulated SR emission is initiated by spontaneous mission from bunch leading edges. In report we describe results of recent experiments and develop a theoretical model which covers both spontaneous and stimulated Cherenkov emission.
A coherent two-channel source of Cherenkov superradiance pulses
A two-channel source of Cherenkov superradiance pulses with the electron-wave systems of identical geometry which is capable of producing 2 × 0.3 GW pulses of duration 2 ns and center frequency 10 GHz has been developed and explored. The channels are powered by a high-voltage driver whose pulse is split into two pulses that are sent through parallel transmission lines. To shorten the voltage rise time in each channel, identical NiZn ferrite-loaded coaxial transmission lines with independently controlled axial bias fields are used.
The uprising of the marginalised: a socio-economic perspective of the Syrian uprising
More than three years after the outbreak of protests in a number of Arab countries, the role of socio-economic factors in these events is attracting more attention. One of the cases that needs more research is Syria. More than three years into the Syrian uprising, the socio-economic roots of the protest movement that became one of the bloodiest civil conflicts in the history of the Middle East need to be examined. While it has been observed that the Syrian uprising, contrary to some ‘Arab Spring’ countries, has been an uprising of more marginalised social groups with a strong role played by poorer segments in the society, particularly rural and rural-to-urban migrants, the socio-economic explanation for this is still underdeveloped. This paper aims at contributing to a better understanding of this issue by examining the political and socio-economic compromise that underlined the rule of the Ba’th party in Syria for four decades and unpacking how a combination of internal and external shifts that started in the 1990s and intensified in the 2000s led to the erosion of this compromise, providing the background to the events that began in 2011.