and Pollock (Indiana University), Improper synchrotrons have frequent efficiency, are the most promising respectively. deviations from symmetry due to approach to economical fusion A tour of the local TRIUMF facility straight sections of unequal length. energy production. However the was preceded by orientation talks on The TRIUMF group put together an need for cost saving in the driver the 520 MeV cyclotron and the interesting and smooth-running accelerator requires new ideas in proposed KAON Factory. Dutto conference, with Mike Craddock target design tailored to the particu­ mentioned that the cyclotron has chairing the international and local larities of heavy ion beams, which been improved by the addition of a organizing committees and Gerardo need to be pushed to the limits of fourth-harmonic cavity at large Dutto the scientific program commit­ high current ançj phase space density radius, increasing the energy gain tee. Details can be found in the 179 at the same time. per turn and thus reducing electro­ papers in the proceedings, published Dieter Môhl (CERN), describing magnetic stripping losses. It can also by World Scientific in December. The performance achieved with CERN be used in the flat-top mode to community looks forward to the next accelerators, showed that individual improve beam quality and extraction. Conference, in 1995, to be hosted by parameters have been close enough Craddock described the KAON NAC, in Cape Town, South Africa. to what is needed for fusion, but no accelerators and how the TRIUMF machine has pushed all parameters beam will be matched to the suc­ David J. Clark, Lawrence Berkeley simultaneously to their limits, which is ceeding rings at 3 and 30 GeV. He Laboratory the real challenge. pointed out how the support for According to Ingo Hofmann (GSI, KAON has been growing with the Darmstadt) the SIS heavy ion syn­ assistance of Dr. KAON and friendly chrotron and adjacent ESR cooling government officials Mr. KAON and storage ring have just opened a new KAON Kim (see photo). During the chapter in heavy ion fusion. These tour visitors were taken above the machines provide unique possibilities cyclotron to be shown a quarter and Heavy ion fusion for machine studies for reactor a dime suspended from another drivers as well as target work with the quarter, demonstrating the power of With controlled thermonuclear fusion first dense plasmas to be produced the TRIUMF magnet and the collec­ holding out the possibility of a prolific by heavy ions. tive strength of Canadian currency! and clean new source of energy, the Problems of a full (five kilometre) At the Conference dinner, master of goal remains elusive after many reactor driver linac are under control, ceremonies Mike Craddock extended years of continual effort. While the according to Horst Klein from Frank­ the congratulations of the cyclotron conventional Tokamak route with furt, provided that target designers community to three American Physi­ magnetic confinement continues to are not going to push the normalized cal Society prizewinners: Henry hit the headlines, other alternatives emittance further down. Blosser and Bob Pollock, for the are now becoming competitive. Parallel to the European efforts with 1992 Bonner Prize, awarded for One possible solution is to confine radiofrequency linac and storage ring design and construction of supercon­ the thermonuclear fuel pellet by high technology, the technologically ducting cyclotrons and a cyclotron- power beams. Current research and innovative induction accelerator injected light-ion cooler respectively; perspectives for future work in such approach is pursued by Lawrence and Reg Richardson of UCLA and inertial confinement was the subject Berkeley Laboratory (presented by TRIUMF for the 1991 Wilson Prize, of the 'Prospects for Heavy Ion Tom Fessenden)They are awaiting for demonstrating phase focusing, Fusion' European Research Confer­ funding of their next $60M ILSE the first synchrocyclotron and the first ence held in Aghia Pelaghia, Crete, project. sector-focused cyclotron. last year. Its main focus was on the Conversion of beam energy into Craddock pointed out this research potential of heavy ion accelerators as soft X-rays ('indirect drive') seems to has revealed two classes of accel­ well as recent advances in target be the magic key now for target erators, 'proper' and 'improper'. The physics with high power lasers and physicists. The X-rays are confined in former are of course cyclotrons, with light ion beams. a radiation case ('hohlraum') with the the perfect rotational periodic sym­ Carlo Rubbia declared that high actual fusion pellet at its centre. Due metry of their sector structure. energy accelerators, with their high to multiple reflections the X-rays

24 CERN Courier, January/February 1993 At the 'Prospects for Heavy Ion Fusion' driven 'hohlraum' (radiation enclosure) targets European Research Conference held in Crete by a simple optical analogue - the radiation last year, laser physicist Richard Sigel of near a lamp, measured by a photocell, Munich's Max Planck Institute for Quantum increases dramatically inside a highly Optics demonstrates the principle of indirectly reflecting cavity.

fusion does not yet exist on any international scale. 'Should there be a European programme on inertial fusion?' asked a panel discussion chaired by Rudolf Bock (GSI). There was a consensus that lasers to demonstrate ignition and heavy ions to make an efficient driver are in the same boat - yet there was no doubt that coming together doesn't neces­ sarily increase the funds. Who would lead such a programme in Europe? What is the cost of a dedicated heavy ion accelerator facility to study target physics close to fusion parameters? The meeting was in the spirit of traditional US Gordon conferences with no proceedings, tutorial introduc­ tions encouraged before each talk and enough time for discussion. About 70 people attended, with a good number of younger people 'forget' the spatial nonuniformity of trons), near to what is required for bringing in new blood. The chairman primary heavy ion or laser beams, fusion. was J. Meyer-ter-Vehn, Max-Planck- and a spherically symmetric com­ According to Erik Storm from Institute for Quantum Optics, Munich, pression of the pellet becomes Livermore an upgrade of their exist­ and the meeting was sponsored by possible. ing NOVA laser facility could achieve the European Science Foundation in The physics of radiative hydrody­ ignition (by indirect drive) with fusion association with the European namics under conditions normally gain exceeding 10 by around the Physical Society. present in stellar matter is now a year 2000, provided the required A tribute was made to strong great challenge for theorists develop­ $400M were made available in time. focusing pioneer Nick Christophilos ing simulation programs, evidenced Inertial fusion with lasers is now as in whose home country the confer­ by Jurgen Meyer-ter-Vehn (Munich), close to reaching ignition as mag­ ence took place. Strong focusing and Stefano Atzeni (Frascati) and Mihail netic fusion. later on construction of the Astron Basko (Moscow). More good news came from (electron) induction accelerator have The biggest obstacle having to wait D. Cook, Sandia Laboratories (New both been fruits of his inventive mind. for declassification of US work in Mexico), who reported on recent inertial fusion, but this could be success with the PBFA II pulsed From Ingo Hofmann relativity imminent. The relative power facility shooting about 50 openness of presentations by leading kilojoules of 9 MeV lithium on hydro­ physicists from classified laser carbon foam obtaining conversion laboratories (Livermore, Sandia and into X-rays. The need for reducing Rochester in the US and Limeil in beam divergence is a major issue for France) was surprising and welcome. future development. Milestones were reported by C. With European collaboration in Yamanaka from Osaka, home of the magnetic confinement well estab­ only unclassified dedicated inertial lished, and with a strong inter­ fusion programme. They have regional collaboration in magnetic achieved 600 times compression of fusion heading towards ITER as a solid matter (producing 1013 neu­ next step, collaboration in inertial

CERN Courier, January/February 1993 25