4 Irradiation Facility and Setup

The heavy-ion species used for the SEE studies on this product were provided and delivered by the TAMU Cyclotron Radiation Effects Facility [6], using a superconducting cyclotron and advanced electron cyclotron resonance (ECR) ion source. At the fluxes used, ion beams had good flux stability and high irradiation uniformity over a 1-in diameter circular cross sectional area for the in-air station (TAMU). Uniformity is achieved by means of magnetic defocusing. The flux of the beam is regulated over a broad range spanning several orders of magnitude. For the bulk of these studies, ion flux of ≈ 10⁵ ions/s·cm² were used to provide heavy-ion fluences of ≥10⁷ ions/cm². For these experiments Silver (¹⁰⁹Ag) at angles of incidence of 0° and 25° were used for an LET_EFF of 49.3 and 54.8 MeV·cm²/mg, respectively. Praseodymium (¹⁴¹Pr) at angles of incidence of 0° and 27.3° were used for an LET_EFF of 66.37 and 74.95 MeV·cm²/mg, respectively. Holmium (¹⁶⁵Ho), at angles of incidence of 0° were used for LET_EFF of 75.82 MeV·cm²/mg. The ¹⁰⁹Ag, ¹⁴¹Pr, and ¹⁶⁵Ho ions used had a total kinetic energy of 1.634, 2.114, and 2.474 GeV, in the vacuum (using the 15 MeV/amu), respectively.

The TPS7H4001-SP test board used for the experiments at the TAMU facility is shown in Figure 4-1. Although not visible in this photo, the beam port has a 1-mil Aramica (DuPont? Kevlar?) 1-in diameter window to allow in-air testing while maintaining the vacuum within the accelerator with only minor ion energy loss. The air space between the device and the ion beam port window was maintained at 40 mm for all ¹⁰⁹Ag and ¹⁴¹Pr runs. For all the ¹⁶⁵Ho the distance was set to 30 mm.

Figure 4-1 Photograph of the TPS7H4001-SP Evaluation Board Mounted in Front of the Heavy-Ion Beam Exit Port at the Texas A&M Cyclotron