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Abstract-The test of the first LARP (LHC Accelerator ResearchPre-stress and support are provided by an Al-shell-based structure pre-loaded using bladders and keys. The coils were fabricated at BNL and FNAL, the shell-based structure was designed and assembled at LBNL, the test is performed at FNAL.In this paper we present the final steps of the development of the first model (LQS01), several upgrades to the test facility, the test results of witness cables, and the short sample limit.

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Recently several Rutherford-type Nb Sn cables for possible use in new magnets for upgrades of the LHC have been measured at CERN. A summary is provided including a comparison of the critical current of various cable types and strand materials versus their respective extracted strand measurements. The conductors were cabled at CERN and Lawrence Berkeley National Laboratory. The summary shows an unsurprising linear relation between the strand and the cable performance. However, assuming that the local peak magnetic field in the conductor is the relevant factor for determining the relation, a discrepancy is found when results from different directions of applied magnetic field on the cable are compared.In this paper it is shown that the critical current as a function of the peak magnetic field in the conductor can change in the range of 7-12% depending on the direction of the applied magnetic field. This effect originates from the superposition of the self field of the conductor and the applied magnetic field. When the direction of the applied magnetic field is changed, the position of the peak magnetic field in the conductor shifts. Mechanical degradation during the cabling process can create a local reduction in the critical current. When the position of the peak magnetic field shifts from a more degraded to a less degraded area, the measured curve of the conductor will change accordingly. The measured effect is in principle present in all cables exhibiting non-uniform cabling degradation but is substantially present in Nb Sn conductors for the reasons mentioned.