Accel–decel extraction system for PIG sources
Accel–decel extraction system for PIG sources
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DOI：
10.1063/1.1430866
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发表时间：
2002-02
影响因子：
1.6
通讯作者：
P. Spädtke;F. Heymach;R. Hollinger;K. Leible;R. Mayr;L. Shi
中科院分区：
文献类型：
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作者：
P. Spädtke;F. Heymach;R. Hollinger;K. Leible;R. Mayr;L. Shi
增加离子束的亮度是任何加速器的典型需求。为了将重离子同步加速器（SIS）填充到空间电荷极限，需要更高的脉冲电流。 UNILAC 的运行脉冲长度高达 6 ms，重复率高达 50 s−1。为了注入 SIS，需要 0.3 s−1 时的 300 μs 脉冲长度。 RFQ 的横向接受度为 138 π mm mrad。根据查尔德定律，从等离子体源中提取的离子电流密度对于空间电荷有限流而言与Φ1.5/d2成正比。其中Φ和d表示引出电压和引出间隙的宽度。产生更高离子电流的一种方法是增加常用提取系统中的提取电压。然而，所需的束流速度由 RFQ 结构固定为 2.2 keV/u。要加速的质荷比可以在 1 到 65 之间，导致总电压降从 2.2 到 143 kV（提取和后加速电压）。另一种方法是减小提取系统中的间隙宽度，但长宽比存在最佳值。为了在低能量下产生较高电流的离子束，以加速-减速（Uacc、Udec）模式运行的三极管提取系统是一种可能的解决方案。通过在第二电极处施加负电势，可以获得更高的提取场强度。研究了引出场、电弧电流和离子能量对引出离子束电流及其发射度的影响。提高离子束的亮度是任何加速器的典型需求。为了将重离子同步加速器（SIS）填充到空间电荷极限，需要更高的脉冲电流。 UNILAC 的运行脉冲长度高达 6 ms，重复率高达 50 s−1。为了注入 SIS，需要 0.3 s−1 时的 300 μs 脉冲长度。 RFQ 的横向接受度为 138 π mm mrad。根据查尔德定律，从等离子体源中提取的离子电流密度对于空间电荷有限流而言与Φ1.5/d2成正比。其中Φ和d表示引出电压和引出间隙的宽度。产生更高离子电流的一种方法是增加常用提取系统中的提取电压。然而，所需的束流速度由 RFQ 结构固定为 2.2 keV/u。要加速的质荷比可以在 1 到 65 之间，导致总电压降从 2.2 到 143 kV（提取和充电）。
Increasing the brightness of the ion beam is a typical demand for any accelerator. In order to fill the heavy ion synchrotron (SIS) up to the space charge limit, higher pulse currents are necessary. The UNILAC is operated with a pulse length up to 6 ms and a repetition rate up to 50 s−1. For the injection into the SIS a pulse length of 300 μs at 0.3 s−1 is required. The transverse acceptance of the RFQ is 138 π mm mrad. According to Child’s law, the ion current density which can be extracted from a plasma source is for the space charge limited flow proportional to Φ1.5/d2. With Φ and d denoting the extraction voltage and the width of the extraction gap. One approach to generate higher ion currents is to increase the extraction voltage in the regularly used extraction system. However, the required beam velocity is fixed by the RFQ structure with 2.2 keV/u. The mass-to-charge ratio which is to be accelerated can be between 1 and 65, resulting in a total voltage drop from 2.2 up to 143 kV (extraction and postacceleration voltage). The other approach is to decrease the gap width in the extraction system, but there is an optimum in the aspect ratio. To generate an ion beam with a higher current at low energy, a triode extraction system operated in accel–decel (Uacc,Udec) mode is a possible solution. By applying a negative potential at the second electrode a higher extraction field strength can be achieved. The effects of extraction field, arc current, and ion energy on the extracted ion beam current and its emittance were investigated.Increasing the brightness of the ion beam is a typical demand for any accelerator. In order to fill the heavy ion synchrotron (SIS) up to the space charge limit, higher pulse currents are necessary. The UNILAC is operated with a pulse length up to 6 ms and a repetition rate up to 50 s−1. For the injection into the SIS a pulse length of 300 μs at 0.3 s−1 is required. The transverse acceptance of the RFQ is 138 π mm mrad. According to Child’s law, the ion current density which can be extracted from a plasma source is for the space charge limited flow proportional to Φ1.5/d2. With Φ and d denoting the extraction voltage and the width of the extraction gap. One approach to generate higher ion currents is to increase the extraction voltage in the regularly used extraction system. However, the required beam velocity is fixed by the RFQ structure with 2.2 keV/u. The mass-to-charge ratio which is to be accelerated can be between 1 and 65, resulting in a total voltage drop from 2.2 up to 143 kV (extraction and pos...