Method for pulling cylindrical crystal from melt

According to a method for controlling the diameter of a crystal (5), a constant crystal pulling speed (13) is maintained and in order to control the diameter, heat radiation onto the lower outer surface of the crystal (5) is influenced by varying the height of an annular gap (12) between a heat shield (10) surrounding the crystal (5) and the surface of the melt. This does not only influence the crystal diameter, but also results in a vertical temperature gradient that remains constant across the diameter of the crystal, thereby increasing the homogeneity of the crystal (5). 用于调节晶体（5）的直径的方法设置的是，维持恒定的晶体升高速度（13），并且为了调节直径，以如下方式对到晶体（5）的下周侧区域上的热入射产生影响，即改变包围晶体（5）的热屏蔽件（10）和熔体表面之间的环形间隙（12）的高度。这不仅对晶体直径产生影响，而且还导致在晶体的直径上恒定的竖直的温度梯度，这提高晶体（5）的均匀性。