Parametric phase locking in an electron rf oscillator.

We propose a way to achieve phase locking of output rf radiation produced by an oscillator driven by a cw electron beam. The locking mechanism is provided by fast periodic modulation of electromagnetic properties of the operating cavity. Ohmic loss and/or the eigenmode frequency are modulated using induced photoconductivity of a semiconductor insert, as affected by a laser with a pulse repetition rate equal to twice the rf frequency.

Long-pulse operation at constant output power and single-frequency mode of a high-power electrostatic free-electron maser with depressed collector.

The Fusion Free-Electron Maser (FFF) is the prototype of a high-power, tunable source of mm-wave radiation, for use on fusion plasma devices. In previous experiments a net output power of 730 kW at 206 GHz was generated in short pulses. The present experiment has been equipped with a system to recover the charge and energy of the spent electron beam.

High-power electrostatic free-electron maser as a future source for fusion plasma heating: experiments in the short-pulse regime.

A high-power, frequency-tunable electrostatic free-electron maser, being developed at the FOM Institute for Plasma Physics "Rijnhuizen," shows lasing at various frequencies. An output power of 730 kW at 206 GHz is generated by a 7.2-A, 1.

Free-electron RF-pulse compressor.

A spatially modulated (corrugated) electron beam provides Bragg-type scattering of two waveguide modes. This allows the use of corrugated beams as quick active elements in rf-pulse compressors. In an illustrative example shown with a peak power compression ratio of 20-40, a 10-20 ns output pulse with a peak power of tens of MW is predicted for a millimeter-wavelength compressor.

Cyclotron resonance maser with a tapered magnetic field in the regime of "nonresonant" trapping of the electron beam.

A different version of the regime of electron trapping is proposed for electron microwave amplifiers. The use of this regime in a cyclotron resonance maser with a weakly relativistic electron beam can simultaneously provide efficiency as high as 50%, a very broad (tens of percent) frequency band, and very weak sensitivity to the spread in electron velocity.

Effective coupling of cyclotron autoresonance maser and "gyrotron" modes on a phase-synchronized electron beam.

For a cyclotron resonance maser (CRM) with a helical axis-encircling electron beam, the possibility of a strong interaction between cutoff (gyrotron) and traveling Doppler-up-shifted (cyclotron autoresonance maser) modes, which are in resonance with the electrons at the same frequency, is demonstrated. This effect can be used in a CRM oscillator of a new type, where the feedback and the mode selectivity for the operating traveling mode are provided due to the excitation of the cutoff mode. According to both the theory and the experiment, such a scheme can provide an effective excitation of the traveling mode with negligibly low losses associated with the cutoff mode.

Effective Co-generation of opposite and forward waves in cyclotron-resonance masers.

A novel type of the frequency-tunable oscillator based on simultaneous generation of the forward and opposite waves at the same frequency, but at different cyclotron harmonics, is proposed. A spatially periodic helical electron beam allows for strong coupling of the waves. The opposite wave provides the broadband feedback and electron bunching, whereas the forward wave amplifies the arising signal and withdraws the rf power from the interaction region.

[On-board equipment-based study of psycho-physiological and biochemical responses dynamics of operators during 135-day isolation in the "Mir" orbital station phantom].

There present the investigative findings of the dynamics of psycho-physiological and biomedical responses of the test subjects during simulated emergencies at different stages of adaptation to 135-day isolation in the Mir orbital station mock-up. Ehe main operating factor of an emergency was the 2-day sleep deprivation in combination with the continuous complex and intensive operator work which included the elements of the professional activity of the cosmonauts, among them the simulation of the regular and emergency docking of the spacecraft. By and large the observed physiological responses were characterized by moderate degree of manifestation, they were of functional character and were adequate for the investigated experimental conditions.

[Human cardiac activity during the 1st hours and days of exposure to antiorthostatic hypokinesia (according to the results of echocardiography)].

Six healthy volunteers (aged 19-24) were exposed to head-down tilt (at-10 degrees) for 7 days. The study revealed phasic changes of intracardiac circulation and the pump function which were not accompanied by contractility disorders. On the whole, the changes represented a manifestation of cardiovascular adaptation to hemodynamic shifts that are typical of this type of simulated weightlessness.

[Effect of a combination of head-down posture and LBNP on human tracking performance and spatial orientation].

Test subjects exposed to a head-down tilt at--30 degrees for an hour participated in the experiment. The use of LBNP during tilting improved precision of arrow orientation on the round-shaped screen (during continuous tracking) but did not influence orientation relative to the gravitational axis and the long axis of the body. The selective effect of LBNP on the orientation can be attributed to the increased importance of inner coordinates due to the pressure of interior walls of the LBNP suit on the foot surface, and blood pooling in the dependent part of the body.

[Effect of an increased level of hydration on human tolerance to orthostatism and the action of LBNP].

Intake of fluid, water-salt solutions, water and sodium chloride resulted in hyperhydration, the level and duration of which varied with respect to the pattern and composition of the ingredients consumed. As applied to real space flights, fractional consumption of water and sodium chloride proved most promising. This regimen yielded a distinct and prolonged hyperhydration and incrased orthostatic and LBNP tolerance of the test subjects.