An electromagnetic pulse protecting method includes: searching a threat 2 that generates an electromagnetic pulse 2a; and generating plasma 6 in a light-condensed point 4 by condensing a laser beam 5 on a light-condensed point 4 in response to detection of the threat 2. Thus, various protection objects which contain a protection object having an electric opening indispensably can be protected from an attack by the electromagnetic pulse.

A compact radio-frequency quadrupole RFQ accelerator for accelerating charged particles, the RFQ accelerator comprising: a bunching section configured to have a narrow radio-frequency rf acceptance such that only a portion of a particle beam incident on the bunching section is captured, and wherein the bunching section bunches the portion of the particle beam; an accelerating section for accelerating the bunched portion of the particle beam to an output energy; and, a means for supplying radio-frequency power.

An electromagnetic pulse protecting method includes: searching a threat 2 that generates an electromagnetic pulse 2a; and generating plasma 6 in a light-condensed point 4 by condensing a laser beam 5 on a light-condensed point 4 in response to detection of the threat 2. Thus, various protection objects which contain a protection object having an electric opening indispensably can be protected from an attack by the electromagnetic pulse.