A curvature-driven flute instability will be excited in the magnetized plasmas if the magnetic field lines curve toward the entire plasma boundary. Conditions under which it can be effectively stabilized in axisymmetric geometry have been experimentally studied in a gas-dynamic trap (GDT) at Novosibirsk. Flexible design of the experimental device and the availability of neutral beams and ion cyclotron heating enabled the pressure-weighted curvature to be varied over a wide range. The stability limits were thus measured and compared with those predicted by the modified Rosenbluth–Longmire criterion. Characteristics of unstable curvature-driven flute modes were also measured and found to conform to a theory including finite ion Larmor radius (FLR) effects. Stable operation during neutral beam injection was achieved with a cusp end cell, resulting in an increase in Te to 45 eV, limited by end losses rather than anomalous power losses.
HIRFL-CSR, a new ion accelerator complex, is under construction at IMP, Lanzhou, China. It is equipped with two electron cooling devices. This article describes the commissioning of cooler at electron energy 300 keV. The cooler is one of the new coolers with some unique features manufactured in BINP, Russia. It has a new electron gun producing a hollow electron beam, electrostatic bending and a new structure of solenoid coils at the cooling section. The test results of cooler are reported.
To provide the maximum possible cooling rate for the Recycler Electron Cooling (REC) [1], the cooling section has to be immersed into a high-quality longitudinal magnetic field. Namely, the solenoidal field of 50-150 G should have an integral of the transverse component below 1 G⋅cm over the whole 20-m cooling section [2]. The transverse field components are measured by a dedicated compassbased sensor [3], which has been designed and manufactured at Budker INP, Novosibirsk. The paper describes results of the field measurements performed on the cooling section solenoid prototypes as well as the design and the calibration procedure of the sensor.
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