H.F. Dylla
A5066360097- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Metal and Thin Film Mechanics
- Gyrotron and Vacuum Electronics Research
- Semiconductor materials and devices
- Nuclear Physics and Applications
- Nuclear Materials and Properties
- Laser Design and Applications
- Advanced X-ray Imaging Techniques
- Ion-surface interactions and analysis
- Electron and X-Ray Spectroscopy Techniques
- Diamond and Carbon-based Materials Research
- Atomic and Molecular Physics
- Vacuum and Plasma Arcs
- Muon and positron interactions and applications
- Mass Spectrometry Techniques and Applications
- Laser-induced spectroscopy and plasma
- Ionosphere and magnetosphere dynamics
- Graphite, nuclear technology, radiation studies
- Radioactive contamination and transfer
American Institute of Physics
2008-2023
Nobel Foundation
2020
Thomas Jefferson National Accelerator Facility
1995-2006
Princeton Plasma Physics Laboratory
1983-2003
Princeton University
1983-2003
Fermi National Accelerator Laboratory
2003
William & Mary
1993-2003
Williams (United States)
1993-2003
Continuous Electron Beam Accelerator Facility
1992-2002
Princeton Scientific (United States)
1990-1992
Jefferson Laboratory's kW-level infrared free-electron laser utilizes a superconducting accelerator that recovers about 75% of the electron-beam power. In achieving first lasing, operated "straight ahead" to deliver 38-MeV, 1.1-mA cw current for lasing near 5 &mgr;m. The waste beam was sent directly dump while producing stable operation at up 311 W. Utilizing recirculation loop send electron back linac energy recovery, machine has now recovered average currents mA, and lased with 1720 W output 3.1
Neutral-beam heating of plasmas in the Tokamak Fusion Test Reactor at low preinjection densities [${n}_{e}$(0)\ensuremath{\simeq}${10}^{19}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$] were characterized by ${T}_{e}$(0)=6.5 keV, ${T}_{i}$(0)=20 ${n}_{e}$(0)=7\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$, ${\ensuremath{\tau}}_{E}$=170 msec, ${\ensuremath{\beta}}_{\mathrm{theta}}$=2, and a d(d,n${)}^{3}$He neutron emission rate ${10}^{16}$...
Background and Objectives In theory, infrared vibrational bands could be used for selective photothermolysis of lipid-rich tissues such as fat, sebaceous glands, or atherosclerotic plaques. Study Design/Materials Methods Absorption spectra human fat were measured, identifying promising near 1,210 1,720 nm. Photothermal excitation porcine dermis measured with a 3.5–5 µm thermal camera during exposure to the free electron laser (FEL) at Jefferson National Laboratory. Thermal damage...
Experimental results from high-power neutral-beam-injection experiments on the Princeton Large Torus tokamak are reported. At highest beam powers (2.4 MW) and lowest plasma densities [${n}_{e}(0)=5\ifmmode\times\else\texttimes\fi{}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$], ion temperatures of 6.5 keV achieved. The collisionality ${{\ensuremath{\nu}}_{i}}^{*}$ drops below 0.1 over much radial profile. Electron heating $\frac{\ensuremath{\Delta}{T}_{e}}{{T}_{e}}\ensuremath{\approx}50%$ has...
A review is given of glow discharge techniques which are useful for conditioning vacuum vessels high-vacuum applications. Substantial development has been done the purpose in situ large ultrahigh systems particle accelerators and magnetic fusion devices. In these applications treatments remove impurities from vessel surfaces order to minimize particle-induced desorption coefficients. Cleaning mechanisms involve a mixture sputtering ion(or neutral)-induced effects depending on gas (Ar/O2 vs...
We report a new experimental technique for testing the electrical neutrality of molecules. An alternating electric field applied to an acoustic cavity containing S${\mathrm{F}}_{6}$ gas will generate sound at frequency if has charge. With suitably calibrated microphone in pressure can be measured yielding upper limit charge per molecule $\ensuremath{\epsilon}$. Dividing by mass number (146) yields electron-proton difference. (This last result assumes that difference equals neutron charge.)...
A number of important applications ultrahigh vacuum technology involve the use systems which cannot be baked in situ, e.g., materials processing equipment and various designs accelerators fusion devices. choice vessel material surface treatment minimizes outgassing unbaked has obvious advantages. We report on a systematic comparison measurements from type 304 stainless steels 6061/63 aluminum alloys after standard advanced treatments. Correlations were made with high-resolution secondary ion...
Following a two-year operational period the Tokamak Fusion Test Reactor (TFTR) graphite fixed bumper limiter has been examined by variety of methods. The areal density metals was mapped in situ beta backscattering. Several tiles were detail nuclear-reaction analysis, Rutherford backscattering, and proton-induced x-ray emission to measure densities deuterium impurities. Some areas found be covered deposited material several microns thick. Other where incident plasma flux is higher much...
Abstract Background and Objectives The success of permanent laser hair removal suggests that selective photothermolysis (SP) sebaceous glands, another part follicles, may also have merit. About 30% sebum consists fats with copious CH 2 bond content. SP was studied in vitro , using free electron (FEL) pulses at an infrared vibrational absorption wavelength band. Methods Absorption spectra natural artificially prepared were measured from 200 to 3,000 nm, determine wavelengths potentially able...
Numerous measurements of outgassing from metal surfaces show that the obeys a power law form Q=Q10t−α, where α is typically near unity. For unbaked systems, dominated by water. This work demonstrates function water vapor exposure during venting system, and physical properties passivation oxide layer on surface. An analytic expression for rate derived based assumption diffusing through to surface governs its release into vacuum. The source distribution desorbing assumed be combination...
The TFTR tokamak has reached its original machine design specifications (Ip=2.5 MA and BT=5.2 T). Recently, the D degrees neutral beam heating power been increased to 6.3 MW. By operating at low plasma current (Ip approximately=0.8 MA) density (ne approximately=1*1019 m-3), high ion temperatures (9+or-2 keV) rotation speeds (7*105 m/s) have achieved during injection. At opposite extreme, pellet injection into plasmas used increase line-average 8*1019 m-3 central 1.6*1020 m-3. This wide range...
A glow discharge technique has been developed and applied to the conditioning of large (38 m3) Poloidal Divertor Experiment (PDX) vacuum vessel. The parameters working gas (H2) were chosen maximize C O removal minimize metal sputtering. was produced by biasing one or two internal anodes at 400 V sustain a current 2–4 per anode. Purified H2 pressure 3×10−2 Torr flowed through PDX ∠10 l/s. effectiveness monitored measuring impurity (CH4, C2H4, CO) exhaust rates mass spectrometry surface in...
A strong pumping effect was observed with plasma operation on the toroidal graphite bumper limiter in TFTR. The induced by conditioning a short series (10-20) of low density deuterium or helium initiated discharges. decay constant for gas fuelled Ohmic discharges reduced from before to minimum after conditioning, which corresponds reduction global recycling coefficient about 100% less than 50%. Coincident conditions, current neutral beam showed energy confinement times were enhanced factor...
Measurements of the toroidal rotation speed vφ(r) driven by neutral beam injection in tokamak plasmas and, particular, simultaneous profile measurements vφ, Ti, Te, and ne, have provided new insights into nature anomalous transport tokamaks. Low-recycling heated with unidirectional exhibit a strong correlation among local diffusivities, χφ≊χi>χe. Recent confirmed similar behavior broad-density L-mode plasmas. These results are consistent conjecture that electrostatic turbulence is...
TSTR (Tokamak Fusion Test Reactor) has operated since December 1982 with ohmically heated plasmas. Routine operation feedback control of plasma current, position and density been obtained for plasmas Ip≃800 kA, a = 68 cm, R 250 Bt=27 kG. A maximum current 1 MA was achieved q≃2.5. Energy confinement times ~150 msec were measured hydrogen deuterium e 2 x 1013 cm-3, Te(0) 2≃1.5 keV, Ti(0) 1.5 keV Zeff≃1 3. The preliminary results suqgest size-cubed scaling from PLT, are consistent Alcator C...
Magnetohydrodynamic (MHD) activity within three zones (core, half-radius, and edge) of TFTR [Plasma Physics Controlled Nuclear Fusion Research 1986 (IAEA, Vienna, 1987), Vol. 1, p. 51] tokamak plasmas are discussed. Near the core plasma column, sawteeth often observed. Two types studied in detail; one with complete, other incomplete, magnetic reconnection. Their characteristics determined by shape q profile. half-radius m/n=3/2 2/1 resistive ballooning modes found to correlate a beta...
The analysis of isotopes hydrogen (H,D,T) and helium (3He,4He) selected impurities using a quadrupole mass spectrometer (QMS) has been investigated as method measuring the purity tritium gas for injection into Tokamak Fusion Test Reactor (TFTR). A QMS was used at low resolution, m/Δm<150, quantifying from m/q = 2 to 44, medium m/Δm∠600, determining concentrations HD in 3He, 4He HT/D2. Sample gases be studied were introduced housing through molecular leak 3‐liter inlet volume. linear relation...