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The possibility of using a weak-focusing ultraminiature synchrotron for generating stable coherent synchrotron radiation at wavelengths 0.5-5 mm is examined. An ultraminiature synchrotron has the following optimized working parameters: electron enegy E = 24 MeV, radius of curvature of the beam orbit R 0 = 0.01592 m, average working beam current I work = 0.022 A, beam lifetime τ = 1000 sec, injection frequency f inj = 0.1 Hz, number of bunches in a beam K = 1, and bunch length σ L = 0.283·10 -3 m. The use of a source greatly simplifies user access to stable coherent synchrotron radiation and expands the range of applications of this radiation.Successful work on generating stable coherent synchrotron radiation in the terahertz range has been completed over the last few years at several previously constructed electron strorage rings (BESSY II, Germany, and others). The measured spectral intensity, which is proportional to the squared number of electrons in the beam, was found to be 10 6 -10 7 times higher than the spectral intensity of previously known wide-band sources of terahertz radiation, such as, ordinary incoherent synchrotron radiation and thermal sources.It is of interest to discuss a possible inexpensive portable source of coherent synchrotron radiation which is suitable for use in small laboratories.Description of the Construction. The construction of a source of coherent radiation based on an ultraminiature synchrotron is shown schematically, neglecting the scaling factors, in Fig. 1. A beam of electrons with energy E inj ≤ 1-3 keV is injected, using an electron gun 1 lying along the vertical symmetry axis of the setup, into a region next to the center of a water-cooled reactangular rf-cavity 4 tuned to the TE 101 mode. The cavity 4 with the dimensions b < a < d and operating at the frequency ƒ 0 = 2.998 GHz lies inside a vacuum chamber (not shown in Fig. 1) which provides an ultrahigh working vacuum P = 1·10 -7 Pa. The magnetic system of the accelerator consists of superconducting coils 2, which produce a constant (in time) guiding magnetic field B con , and coils 3, which generate a pulsed magnetic field B pul directed in a direction opposite to B con . The electrons are entrained into acceleration at the moment the total magnetic field ΣB = B con -B pul reaches the value of the magnetic field of the cyclotron resonance for the angular frequency ω rf of the cavity. At this moment, the pulsed magnetic field reaches its amplitude value. As the pulsed magnetic field subsequently decreases, the electrons are accelerated up to the working energy E work in the total guiding magnetic field which is increasing in time.The method of generating pulses of a magnetic field was previosuly mentioned in, for example, [1]. After being entrained into acceleration, the electrons move from the center to the periphery of the cavity along spiral trajectories with instantanteous radius R = βc/ω rf , where β = v/c, v is the instantaneous orbital velocity of an electron, and c is the speed of light. As β → 1, a circular relat...

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The use of a subminiature electron storage ring in the weak-current regime (I b = 0.02 mA) as a source of coherent mm-range synchrotron radiation and a laboratory facility for studying electron scattering in a bunch is studied. The weak-current regime considerably simplifies the construction of a magnetic system and decreases the likelihood of the development of bunch instabilities. To make a more accurate assessment of some basic parameters of a subminiature storage ring, a calculation of the effective accelerating voltage was performed taking account of the transit factor of the rf-system cavity.A particularity of the weak-current regime is the simplicity of its implementation. Before the application of the weak-current regime is discussed, the amplitude of the effective accelerating voltage is calculated taking account of the transit factor of the cavity and methods for calculating the beam lifetime are analyzed.Calculation of the Accelerating Voltage. In a subminiature storage ring [1,2], the orbit of the beam lies inside the cavity of the rf system, while in ordinary storage rings it passes through the rf cavity.The amplitude of the accelerating rf voltage U max and the energy acquired by an equilibrium particle over one revolution ΔE rev are related with one another by the well-known equation

Two simple analitical formulae to evaluate a lifetime of a stored electron (positron) beam at storage ring have been derived. Comparison between the lifetimes measured under typical operation conditions and calculated values has been carried out.