[en] A261. A CREDIBLE PATHWAY FOR HEAVY ION DRIVEN TARGET FABRICATION AND INJECTION

[en] A261. A CREDIBLE PATHWAY FOR HEAVY ION DRIVEN TARGET FABRICATION AND INJECTION

[en] The relationship between target gain (thermonuclear energy-released/ion energy incident) and such factors as the total ion energy, the ion beam radius, the ion range, the ion power, the beam geometry, and the released target debris are critical in assessing the feasibility of a particular heavy ion inertial confinement fusion reactor concept. Scaling relationships that allow target gain to be calculated from the target hydrodynamic coupling efficiency (eta), the target radius (R), and the ion energy incident on the target (E/sub i/) are presented. These relations include scaling laws for the required peak power and ion energy, the fuel fractional burnup, and the fraction of energy released in charged particles and x-rays as a function of r, eta, and E/sub i/. Relations have been developed to two single-shell target concepts, one requiring two-sided and the other symmetric ion illumination

[en] The prototype of the Super High Voltage System (SHVS), eight stages induction adder, was developed and a output of 3.2 MV, 100 ns was achieved. The ion diode experiments of beam bunching on SHVS were performed with plasma injection ion source. Injection ion source improved the turn-on delay to be better than 5 ns. Experimental results shows that the risetime of downstream ion charge collector signal become a half of upstream detector due to the beam bunching. The pure ion source is necessary to bunch the beam. (author)

[en] At the MPI fuer Kernphysik, a new type of accelerator is under construction which consists of a CHORDIS ion source, two RFQ and eight 7-gap resonators. The high current injector will deliver 1-3 orders of magnitude higher intensities in comparison to the existing tandem-postaccelerator combination. The RFQ is designed to accelerate ions with a minimum charge to mass ratio of q/m = 1:9 up to an energy of 0.478 MeV/u. Both resonators operate at a frequency of 108.48 MHz with a pulsed power of 90 kW (25% duty factor (DF)). By means of an optimizing algorithm, it was possible to lower the electrode voltage of the RFQ-accelerator from 71 kV to 60 kV maintaining a slightly reduced final energy and a particle transmission of about 80% with ion currents of 10 mA. A new electrode profile was developed in order to combine sufficient cooling with good mechanical stability. Moreover the fabrication process of the RFQ-stems and the electrodes were simplified and optimized. Both resonators are tuned and tested with low level measurements and under high power with a H₂⁺-ion beam. (orig.)

No abstract available

[en] The issues of ion beam transport are studied in the context of the LIBRA-LiTE reactor study. LIBRA-LiTE is a 1000 MWe power plant design consistent with ballistic ion focusing. The ion beam energy must be divided between many beams to provide proper illumination symmetry. The needs to keep the total beam energy low and the intensity at the required level lead to constraints on the transport system, particularly, a high degree of bunching and a low microdivergence. This paper will describe arguments leading to an operating point for light ion ICF with ballistic focusing. Calculations of heating of the background gas by the ion beams and the subsequent increase in the electrical conductivity of the gas will be presented. This is an important issue to the stability of the ion beam

[en] The CASTOR accelerator has been fitted with an applied B_r extractor diode for use in ion beam transport and focusing experiments. The beam, composed mainly of protons, is accelerated to 300-400 keV. Beam propagation in vacuum is observed to be consistent with divergences of 50 mrad HWHM in the radial direction and 125 mrad HWHM in the azimuthal direction and is observed to be constant through the beam pulse. Collective focusing of protons and electrons by a solenoidal lens is observed. The radial profile of the focus is as expected for the measured divergences. Improved focusing due to a lens system that simultaneously compensates for radial divergence and beam energy spread has yet to be demonstrated. Long time scale conductivities of 0.5-1.0 x 10¹³ s^-1 are measured in beam ionized nitrogen plasmas

No abstract available

[en] A conceptual scheme is presented which combines self-consistently a hohlraum target design at the input energy E_dr = 10 MJ with a scheme for a charge-symmetric heavy ion driver capable of producing the pulse power profile and the focal spot size required for target ignition and high energy gain. The physical issues underlying the key aspects of the target performance are put together into a coherent theoretical scheme which allows the target parameters to be rescaled to other values of E_dr. Special attention is paid to the method of pulse shaping in the final stages of beam compression by taking advantage of four different platinum isotopes employed in the driver scheme. It is found that a heavy ion fusion facility designed along the same lines for a considerably lower input energy E_dr ∼ 2 MJ would require a power pulse of 2.5-3 ns, which appears to be prohibitively short for present accelerator technology. (orig.)