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Transient beam loading effects and microwave instability are very important in ion synchrotrons. A simulation code longitudinal particle tracking code (LPTC) based on multiparticle tracking is developed to simulate the beam loading effects and the longitudinal beam instabilities in the booster ring (BRing) of the High Intensity heavy-ion Accelerator Facility (HIAF). A process of beam capture, acceleration, debunching, and the second capture is simulated with a reference ion beam of ^{78}Kr^{19+}. The simulation results show that the beam loading effects have major contribution to the beam behavior during the debunching stage and the second capture stage. A feed-forward system is suggested to compensate the beam loading effects, and the main parameters of the feed-forward system are given. The microwave instability of coasting ^{78}Kr^{19+} beams is observed from the simulation results. The threshold of the microwave instability is also given. The development of self-bunching and methods to suppress the microwave instability in the BRing are discussed.

The transverse broadband impedances of major components in the BRing (booster ring) of HIAF (High Intensity Heavy-ion Accelerator Facility) are estimated using the analytical formulas or the wakefield solver in the CST Studio Suite. At low frequency, the transverse broadband impedance model of BRing is Z_{1}^{H}(ω)=-417.14i kΩ/m(horizontal) and Z_{1}^{V}(ω)=-530.19i kΩ/m(vertical), which are larger than the threshold impedance for the transverse mode-coupling instability. The ceramic rings in the vacuum chamber are the primary source of impedance. With a goal of mitigating the instability by reducing the impedance of ceramic rings, a high conductivity coating is discussed in detail. In addition, a prototype of ceramic rings-loaded thin-wall vacuum chamber is manufactured and the impedance measurements are performed. When ceramic rings are coated by 2 μm-copper, the CST simulation and experiment results show that the transverse broadband impedance of ceramic rings-loaded thin-wall vacuum chamber can be reduced from Z_{1}^{H}(ω)=-291.69i kΩ/m and Z_{1}^{V}(ω)=-352.37i kΩ/m to Z_{1}^{H}(ω)=-46.16i kΩ/m and Z_{1}^{V}(ω)=-64.56i kΩ/m. Furthermore, in this case the transverse broadband impedance model of BRing is reduced by more than 50% to Z_{1}^{H}(ω)=-171.61i kΩ/m and Z_{1}^{V}(ω)=-242.38i kΩ/m.

Evaluation of transverse impedances and collective instabilities is important for determining whether a transverse feedback system or damping schemes should be prepared in the BRing (Booster Ring) at the HIAF (High Intensity Heavy-ion Accelerator Facility). In this paper, some dominant transverse impedances are estimated to build a transverse impedance model of the BRing. With this model, all potential transverse instabilities and their growth times or rates are analyzed by analytical methods or simulations, and the results agree with each other. The growth times of some instabilities are shorter than the duration times of corresponding manipulations, which shows transverse instabilities may have many detrimental impacts on the BRing. To cure the transverse instabilities, a transverse feedback system will be proposed in the design of the BRing. Besides, this paper not only shows the transverse instabilities in the BRing, but also provides the whole method for estimating them in the design of a new accelerator facility.