The injector scheme I (injector-I) of China ADS test stand is a superconducting Linac which accelerates 10mA beam to 3.2MeV, 5MeV, 10MeV, and then transports it to the dump [1]. The dump line is designed to meet the requirement of beam expansion at the three different energies. The XAL [2] from SNS was selected for the commissioning of China ADS. Because the beam current is so high, the nonlinear space charge force cannot be omitted. As we know, XAL calculates the space charge force with linear resolver. So, whether it could display the beam exactly enough is an important issue to consider. As a preparation for beam commissioning, the virtual accelerator in XAL frame was built and tested. Here in this paper, the envelopes of the 5MeV and 10MeV lattices from general XAL mpx application are shown and compared with the multiparticle tracking code TraceWin. INTRODUCTION The China-ADS (Accelerator Driven subcritical System) project is a strategic plan to solve the nuclear waste problem and the resource problems for the nuclear power. The ADS driver Linac has very high beam power and reliability requirements which are not possessed by any of the existing accelerators. The test stand of China ADS is one of the experimental efforts for the ADS projects. The Injector-I is a superconducting Linac which is being constructed in hall 1 of IHEP. It is consists of MEBT1, CM1 for 5MeV and 10MeV, CM2 for 10MeV, and MEBT2. After optimizing the lattice and consulting with people of other accelerator systems over and over again, the final lattice is finally determined. Figure 1 shows the 10MeV lattice layout. It contains two cryomodules, each of which contains seven periods. Every period contains one superconducting solenoid and one superconducting RF cavity (single gap spoke cavity). Figure 1: 10MeV lattice layout of injector-I of China ADS test stand. One cryomodule contains seven periods. Each period consists of one superconducting solenoid and RF cavity. For 5MeV lattice, the superconducting section is just CM1, while for 3.2MeV both the CM1 and CM2 are not needed. Figure 2: 10MeV beam envelope from Partran of TraceWin. The envelope in MEBT2 is much larger than that in the front section. ___________________________________________ *Work supported by the CAS Strategic Priority Research ProgramChina-ADS. #zhaoyl@ihep.ac.cn 5th International Particle Accelerator Conference IPAC2014, Dresden, Germany JACoW Publishing ISBN: 978-3-95450-132-8 doi:10.18429/JACoW-IPAC2014-THPME138 THPME138 3572 Co nt en tf ro m th is w or k m ay be us ed un de rt he te rm so ft he CC BY 3. 0 lic en ce (© 20 14 ). A ny di str ib ut io n of th is w or k m us tm ai nt ai n at tri bu tio n to th e au th or (s ), tit le of th e w or k, pu bl ish er ,a nd D O I. 06 Instrumentation, Controls, Feedback & Operational Aspects T03 Beam Diagnostics and Instrumentation For 5MeV, the superconducting section is just CM1, while for 3.2MeV; both the CM1 and CM2 are not needed. The 10MeV beam envelope from Partran of TraceWin is shown in Figure 2. In the figure, we can see, the envelope in MEBT2 is much larger than that in the front section. So, in the follow parts of the particle, we just compare the envelope before MEBT2. 5MEV ENVELOPE COMPARASION The fields of superconducting cavities, solenoids and bunchers in MEBT1 are treated as field_map elements in TraceWin code, while as ideal field in XAL. We track the beam in TraceWin with Partran method and matrix method. Similarly, the tracker of the probe in mpx application, XAL frame, is set to be “EnvelopeTracker”. For low beta superconducting linac, the velocity increasing in a RF cavity is large and cannot be seen as perturbation. The transit time factor for beam is changing with beta, what means, transit time factors T, S, T’, S’, isn’t enough to display the real affections the cavity to the beam. Here the attributes E, T, L in “RfGapBucket” of XAL are replaced with one attribute ETL [3]. Lattice Table 1 is the values of the main parameters of 5MeV lattice. Table 1: Main Specifications of the 5MeV Lattice of Injector-I