Systems 1 T ii:. Injoetior Savelonaent I'.) rjt. Proton injector. 20 it. Carbon Flaana duns.. '' 31 C. Injector Gap. . i .-39-6. Jfl)d5fe^f (Injector BejSjarior 5« IV. Heptarsitliiicesi PiCjiagatl.on of Ion leas. ' 6; .'. Post-Acceleration of High Intensity Ion Beams 72 71. Poetising of Ian Beaas In ' A Post-Acceleration Gap 88 VI!. Conclusions 9<> AcJuswtf.«jSaewe»* ....'. 99 SfesWMHK* 110' •' '-AP?£3DtX /' I.-CiWjpftlafeSoriB of the Magnetic Field end Singly f«rtiAei!ft Son Orbit* in ia>e Pulselac 54? •'v_^r ^0? II. ,100 Bean Louses and Seconder Electron Production ....
The emerging capability to produce high average power (10-300 kW) pulsed ion beams at 0. Deposition of the energy in a thin surface layer allows melting of the layer with relatively small energies (1-10 J/cm2) and allows rapid cooling ofthe melted layer by thermal conduction into the underlying substrate. Typical cooling rates of this process (109 Wsec) are sufficient to cause amorphous layer formation and the production of non-equilibrium microstructures (nanocrystalline and metastable phases). Results fiom initial experiments confirm surface hardening, amorphous layer and nanocrystaline grain size formation, corrosion resistance in stainless steel and aluminum, metal surface polishing, controlled melt of ceramic surfaces, and surface cleaning and oxide layer removal as well as surface ablation and redeposition. These results follow other encouraging results obtained previously in Russia using single pulse ion beam systems.Potential commercialization of this surface treatment capability is made possible by the combination of two new technologies, a new repetitive high energy pulsed power capability (0.2-2MV, 25-50 kA, 60 ns, 120 Hz) developed at SNL, and a new repetitive ion beam system developed at Cornell University.
A relatively long-pulse width (0.1–1 μs) intense ion beam accelerator has been built for materials processing applications. An applied Br, magnetically insulated extraction ion diode with dielectric flashover ion source is installed directly onto the output of a 1.2 MV, 300-kJ Marx generator. The diode is designed with the aid of multidimensional particle-in-cell simulations. Initial operation of the accelerator at 0.4 MV indicates satisfactory performance without the need for additional pulse shaping. The effect of a plasma opening switch on diode behavior is considered.
A magnetically self-confined ring of 430-keV protons with a field reversal on axis of 3% is formed in an 8-kG solenoid, as evidenced by propagation more than 1 m in 15-400 mTorr air or hydrogen without dispersion. Up to 83% of the proton kinetic energy is in rotation and inductive coupling of axial ring energy to azimuthal plasma current induced in air (but not hydrogen) gives reflection of >50% of the ring from a 23% mirror.PACS numbers: 52.55.Ke Magnetic field configurations in which an externally applied magnetic field is reversed by currents flowing in the plasma itself are expected to have favorable plasma confinement properties and have, therefore, attracted considerable interest for fusion reactors. The current may be carried by either low-energy plasma particles or by rings of high-energy particles. Synchrotron radiation losses by energetic electrons, the possibility of plasma heating by the energetic ions, 1 and theoretical predictions of a more stable configuration 2 have lead to field-reversal schemes with use of high-energy ions. Recent developments in intense ion-beam technology have made it possible to attempt single-pulse injection and trapping of a field-reversing proton ring in a mirror well on a time scale of 0.1-1.0 jmsec. Indeed, the transient reversal of an applied magnetic field by a rotating proton beam has recently been reported, 3 although the average axial velocity and its dispersion are too large for the beam to be trapped in a mirror well or confined in its own diamagnetic well.In this Letter we report experimental results on the formation and dynamics of a rotating proton ring, whose quality is such that particles are trapped in their own 3% diamagnetic well. To summarize, an annular ~430-keV proton beam from a magnetically insulated diode is injected through a cusplike magnetic field to form a rotating proton beam. With
The propagation of an ion ring in a 2.5 m long, 0.30 m diam magnetized plasma column was studied using an axial array of magnetic probes and fast proton detectors, a microwave interferometer, and a grating spectrometer. The ring propagated with an initial axial velocity 3×106 m/sec, about four times the Alfvén speed in the plasma, and excited damped magnetosonic waves whose peak amplitude depended on the plasma return current. The plasma electrons were heated by about 1 eV in response to the ring, as measured by the Hγ line-to-continuum intensity ratio. This heating is primarily attributed to classical Coulomb collisions, although about 1%–10% can be attributed to the collective ring–plasma interaction. The collective interaction had no measurable effect on the dynamics of the ion ring, consistent with theoretical models, given the beam, plasma, and magnetic-field parameters in the experiment.
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