Protons frora d(d,p)t fusion reactions have been observed in the Princeton Large Torus (PLT) using a surface -barrier detector. The time evolution of the escaping protons agrees with the d-d neutron evolution. The proton energy spectrum was measured during ohraic, lower-hybrid, and ICRF heating. The proton spectrum during lower-hybrid heating indicates non-thermal enhancement of the d-d fusion rate. Present Address: Los Alamos National Laboratory, Los Alamos, New Mexico 87545 -2-In a deuterium

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... lasma, 3.0 MeV protons are produced by d(d,p)t fusion reactions in nearly equal numbers as 2.45 MeV neutrons from d(d,n) 3 He reactions. These protons have previously been detected in plasma experiments using emulsions* and with a silicon surface barrier detector. In this work, the first time -and energy -resolved measurements of these protons escaping from a tokamak plasma have been used as a diagnostic of the reacting deuterons during ohmtc and auxiliary heating experiments. The proton time evolution agreed with the evolution of the d-d neutron emission. The proton energy spectrum during ohmic or 3 He minority Ion Cyclotron Range-of-Frequency (ICRF) heating was consistent with thermonuclear d-d reactions. The width of the proton spectrum during lower hybrid heating was much broader and indicated that the reactions were due to a non-Maxwellian deuterium distribution. Non-thermal fusion production was previously inferred in the Alcator A lower hybrid heating experiment. These proton measurements were performed in the Princeton Large Torus (PLT) (major radius -~ 132 cm, minor radius = 40 cm, magnetic field =l/3) and that the rms deviation of F determines the width of a gaussian distribution, we find that Energy spectra of both d-d protons and 14.7 MeV d-He protons " were observed di-ring second harmonic ICRF heating of 3 He ++ ions in a deuterium plasma. The ICRF fast waves were launched from the large major radius side with a pair of half-turn antennae excited at 42 MHz. The second harmonic 3 He layer was located near the magnetic axis by using a toroidal magnetic field of 2i kG. The line-averaged deuterium and %e densities were 2.5 x 10 1 -1 cm and 0.2 x 10'3 c«" , respectively. The measured spectrum (Figure 4) shows the d-d proton peak at 2.6 MeV with FWHM of 0.25 MeV, which is consistent with the detector response for thermonuclear d-d reactions. A peak due to d-3 He protons appears near 14 MeV with FWHM of 2 MeV reflecting the energetic 3 He tail produced by the second harmonic heating. The peak at 6 MeV is a pulser, connected to the detector preamp, used to monitor the noise contribution (0.15 MeV) to the detector resolution. More low energy counts (below 2 MeV) are present in this spectrum. A possible explanation is that the 1000 pm thick depleted region needed to collect the d-3 He proton energy increases the energy which can be deposited by Compton electrons from hard X rays. -5- The d-d proton spectrum measured during lower hybrid heating shows broadening characteristic of deuterium tail formation. In general, these measurements duplicated the d-d neutron time histories but provide / (.'vantages for d-d spectral measurements over neutron spectrometers (although with poorer resolution in these preliminary measurements). These advantages include greater dynamic range than ^He Ionization chambers, moderate spatial resolution, and reduced influence of scattering without the need for massive collimators. The energy resolution of the protOii detectors can be iiaproved by reducing the £ ill thickness and narrowing the entrance apertures. ACKNOWLEDGMENTS