Important advances have been made recently in the invention and application of experimental methods to control the sawtooth instability in tokamak plasmas. The primary means of control involves the application of either ion cyclotron resonance heating, or electron cyclotron heating, with resonance very close to the q = 1 radius in the plasma core. Reported here are experiments which have succes...

The spectrum of cyclotron radiation is calculated for anisotropically distributed relativistic electrons with a nonrelativistic velocity scattering across the magnetic field. It is shown that if such electrons are responsible for a formation of the ”cyclotron” line in the spectrum of Her X-1, then the value of its magnetic field (3 − 6) · 10 Gs following from this interpretation is in a good ag...

An electron beam passing through a metamaterial structure is predicted to generate reversed Cherenkov radiation, an unusual and potentially very useful property. We present an experimental test of this phenomenon using an intense electron beam passing through a metamaterial loaded waveguide. Power levels of up to 5 MW are observed in backward wave modes at a frequency of 2.40 GHz using a one mi...

A cyclotron-resonance maser (CRM) is implemented in a periodic quadrupole waveguide. The device oscillates at the fundamental and high harmonics of the cyclotron frequency. This CRM employs a tenuous low-energy electron beam ( approximately 10 keV, 0.2 A). The periodic structure consists of an array of disks along the quadrupole transmission line, hence it combines both azimuthal and axial peri...

Fixed Field Alternating Gradient accelerators (FFAGs) offer higher pulse repetition rates and acceptances than synchrotrons – and therefore much higher beam intensities. With a fixed magnetic field the rep rate is set by purely rf considerations, and can be several kHz, while the radially extended spiral orbit and high momentum compaction lead to large radial and momentum acceptances – at the c...

For self-consistent ion-beam simulations including electron motion, it is desirable to be able to follow electron dynamics accurately without being constrained by the electron cyclotron timescale. To this end, we have developed a particle-advance that interpolates between full particle dynamics and drift motion. By making a proper choice of interpolation parameter, simulation particles experien...

The spectral properties of a hybrid steady thermal-nonthermal isotropic plasma are studied. The involved emission mechanisms are thermal bremsstrahlung, nonthermal bremsstrahlung, cyclotron and nonthermal synchrotron. Formulas are derived to calculate the emissivities and absorption coefficients of all these processes. Calculations show that the nonthermal synchrotron and the thermal bremsstrah...