Synchrotron resonance maser

Attention is drawn to an obscure formula derived from relativistic quantum electrodynamics in the mid-'60s by Sokolov and Ternov for induced absorption and emission from highly relativistic electrons in a static uniform magnetic field. From their results, we develop handy formulae and graphs to help in preliminary designs for radiation sources to operate at high synchrotron harmonics. Approximate design parameters are given for 100 kW oscillators operating at wavelengths below 3mm, employing magnetic fields of less than 12 kG. It is shown that the Sokolov-Ternov formula can also be deduced from classical relativistic plasma wave theory, but for a numerical factor in one term. This term is shown to describe a gain mechanism which has apparently received scant notice in the gyrotron literature.     

A "C"-band rutile traveling-wave maser

The development of a traveling-wave maser (TWM) with an iron-doped rutile active crystal and a meander line slow-wave circuit is described. This maser exhibited high-quality performance over a frequency range of 5.4 to 5.9 Gc. Iron-doped rutile exhibited a fast recovery time from saturation signals (3.5 ms). Inversion ratios of 10 to 1 were obtained with conventional microwave pumping techniques and a two-pump technique provided ratios of 13 to 1. This maser has been operated with a superconducting magnet.     

A superconducting magnet system for free-electron cyclotron maser

A superconducting magnet system for free-electron cyclotron maser is developed. This system includes a main superconducting magnet, a gradient superconducting magnet, a normal magnet, a cryostat and some accessories. The designed magnet system has the advantages of having a small size, high stable magnetic field and suitable field profile. It is very suitable for a 4mm wavelength free-electron cyclotron maser. The design and some experimental results are given.     

Double-stream electron cyclotron maser

A new mechanism for stimulated radiation combining the cyclotron instability with the plasma double-stream instability is presented. It can be regarded as a new type of electron cyclotron resonance maser (ECRM) (Hirshfield 1979, Liu 1979) as well as a two-stream free-electron laser (FEL) (Piestrup 1981, Bekefi and Jacobs 1982) in a broader sense. One can say that this device combines ECRM and the two-stream FEL into one. The linear theory of the double-stream ECRM is given. Numerical calculations show that it offers the attractive advantages of high gain and broadband as compared with the conventional ECRM.     

High-gain plasma Cerenkov maser

The linearized fluid and Maxwell's equations are used to calculate the dispersion relation for the transverse magnetic modes of a partially filled, plasma-lined, cylindrical waveguide interacting with a relativistic electron beam. Both the plasma liner and the electron beam are assumed to be cold, and the system is immersed in an infinite axial magnetic guide field. The dispersion relation is then used to calculate the growth rate for the instability between the slow-wave modes (Trivelpiece-Gould modes) of the plasma guide and the slow-space charge mode of the electron beam. The calculation is done in the high-gain, strong coupling limit     

Ferric-doped-rutile 8 mm maser

An experimental iron-doped-rutile travelling-wave maser having an electronic gain of 8 dB/cm at signal frequencies in the range 34.5?35.5 GHz has been produced. The device is operated at 4°K; a filled-waveguide structure is used with composite taper/quarter-wave matching sections. The insertion loss of this type of structure is approximately 1 dB/cm.     

Travelling-wave 8 mm maser

A prototype iron-doped-rutile travelling-wave maser has been developed; this maser operates in the 34?36GHz frequency range. Using a 5cm-long 900-parts-per-million-concentration crystal, typical gains of 20dB are obtained with bandwidth of 50MHz at 1.7° K. The noise temperature (without second-stage contribution) is less than 45° K.     

Wide tuning range S-band maser

A low-noise amplifier, operating over the wide tuning range of 1.9 to 3.1 GHz with 5- to 20-MHz bandwidth and 25-dB minimum gain, has been packaged for antenna mounting. Noise temperature is less than 10 K across the band.     

单原子微波激射器中的压缩

利用Jaynes-Cummings模型研究单原子微波激射器中光场的量子起伏,得到了场正交分量的方差的一般表达式。并讨论了一种常见初态的最佳压缩及其时间演化。作为例子,详细研究了初始为热平衡分布的裸原子系统的压缩行为。     

A time-dependent non-linear theory of ion channel electron cyclotron maser

A time-dependent non-linear theory is developed for ion channel electron cyclotron maser (ICECM), and the corresponding numerical calculation results are given for the first time. The theoretical analysis shows that the longitudinal plasma wave tends to enhance the energy exchange between the beam and wave. Using the numerical calculation of the self-consistent time evolution of scattering wave growth, the non-linear effect of ion density on the beam-wave interaction efficiency has been studied. The time norm, which must be satisfied in the operation of ICECM, is verified. Taking 6.8?×?10¹³?cm^?3 ion density, 1?MV accelerated voltage and 1.5?KA beam current, the present numeric calculation results show that the pulse scattering wave power and the frequency can achieve about 200?MW and 284?G?rad/s respectively.     

The optically pumped rubidium maser

The optically pumped rubidium maser oscillator is the most recent addition to a growing number of atomic frequency standards. It is the first atomic frequency standard which is small enough and simple enough to be considered as a replacement for crystal oscillators. These factors and the extreme phase stability which results from the maser action make this device unique among all frequency standards. The device generates a microwave output at the ground-state hyperfine frequency of Rb⁸⁷(6835 Mc/s). The maser consists of a microwave cavity filled with Rb⁸⁷vapor and nitrogen gas. Oscillation occurs when the vapor is illuminated with filtered rubidium resonance radiation. The power output of the maser is 10^-10watts, and higher powers can be expected. In this paper the physical principles and construction of the device are described. The effects of optical pumping, buffer gas, and temperature on the maser are discussed, and experimental results are given. The short-term stability for observation times of about one second is expected to be about one part in 10¹². This may be increased by an order of magnitude by increasing the powser output to 10^-8watts. The long-term stability is expected to be comparable to that obtained in the passive rubidium standard (about one part in 10¹¹per month). These slow fluctuations arise from pressure shifts, light shifts, cavity pulling, and changes in the chemical composition of the buffer gas. The long-term stability can be improved by using the rubidium maser as the flywheel for an atomic beam frequency standard. Such a combination could be expected to have both long-term and short-term stabilities as great as one part in 10¹³.     

Theory of optical maser amplifiers

The interaction between an electromagnetic (em) pulse and a maser medium is described by a general set of five equations, under the assumption of a homogeneously broadened electric-dipole transition with two Bloch relaxation times T2and T1and of a linear broadband loss mechanism. When the equations are specialized at resonance, their solutions include the results of the previous treatments on the amplifier problem obtained under particular assumptions. The steady-state pulse (S. S. P.) introduced by Wittke and Warter forT_{2}/T_{1} = 0is here generalized forT_{2}/T_{1} neq 0and it is shown to propagate at the same velocity of the light in the medium. In the caseT_{2}/T_{1} = 0the steady state is described by exact analytical relations. For times short in comparison to the relaxation times, a solution is given which generalizes the usual interaction formula between an em field and a two-level system by introducing propagation effects. In the general case out of resonance, it is shown that an S. S. P. exists, and that its frequency coincides with the frequency of the atomic transition, independent of the frequency of the input field.     

Large storage box hydrogen maser

An atomic hydrogen maser has been operated that confines atoms in a volume whose linear dimensions are approximately ten times larger than those of previous masers of this type. The uncertainties associated with the wall frequency shift, presently the principal limiting factor in the absolute accuracy of frequency measurements with the hydrogen maser, should be reduced with this device, since the fraction of time an atom spends on the storage box wall is inversely proportional to the diameter of the box. Oscillations are achieved by the use of two resonant cavities coupled by a high-gain amplifier. The strong field maintained in one cavity prestimulates the atoms to radiate at an enhanced rate in the weak field of the other. With enough gain, self-sustained oscillation can be achieved at normal hydrogen fluxes and normal cavityQ-factor values. The theory of the two-cavity large storage box maser is considered and preliminary results are discussed.     

Pulsed electron cyclotron maser experiments

The construction and operation of two pulsed electron cyclotron masers are reported. Measurements of the microwave outputs are presented and compared. The first experiment uses a shielded diode to produce a pulsed electron beam, τ ? 1 μS, 10A ≤ I ≤ 100 A. This annular beam is passed through a multimode cavity to which a magnetic field, which may be varied from 0·1T to 0·6 T, is applied, X-band emissions of up to 100 kW are measured. The second experiment uses a field-immersed diode, which produces an electron beam current of up to 1 kA. The applied magnetic field can also be varied up to 0·6 T in this experiment. Witness-plate results demonstrate that stable beam propagation is achieved. The measured power of the microwave emission is no greater than in the first experiment, but the pulse length is observed to increase by a factor of between 3 and 5, depending upon the conditions, as the magnetic field is increased.