Electron self-injection and acceleration in a hollow plasma channel driven by ultrashort intense laser pulses

The self-injection and acceleration of electrons in a hollow plasma channel driven by ultrashort intense laser pulses is investigated by Particle-in-Cell(PIC) simulations. It is shown that electrons from the bubble sheath will be self-injected into the hollow plasma channel and move radially towards the channel border due to the lack of focusing force in the hollow plasma channel. After several reflections near the channel wall by the strong focusing force, a self-injected electron bunch can be confined in the hollow plasma channel and quasi-phase-stably accelerated forward for the whole laser–plasma interaction process. These electrons using optical and plasma-related self-injection method can be self-organized to remain in the rear of the bubble, where the accelerating electric field is transversely uniform and nearly plateau along the propagation axis. Therefore, the self-injected electron bunch can be accelerated in a steady state without obvious oscillation and has a high quality with narrow energy spread and low divergence.

Analysis and experiments of self-injection magnetron

Magnetrons are widely used in microwave-based industrial applications, which are rapidly developing. However, the coupling between their output frequency and power as well as their wideband spectra restricts their further application. In this work, the output frequency and power of a magnetron are decoupled by self-injection. Moreover, the spectral bandwidth is narrowed, and the phase noise is reduced for most loop phase values. In order to predict the frequency variation with loop phase and injection ratio, a theoretical model based on a circuit equivalent to the magnetron is developed. Furthermore, the developed model also shows that the self-injection magnetron is stabler than the free-running magnetron and that the magnetron＇s phase noise can be reduced significantly for most loop phase values. Experimental results confirm the conclusions obtained using the proposed model.

Comparative study on pump frequency tuning and self-injection locking in Kerr microcomb generation

The optical frequency comb has attracted considerable interest due to its diverse applications in optical atomic clocks,ultra-low-noise microwave generation,dual-comb spectroscopy,and optical communications.The merits of large frequency spacing,high integration,and low power consumption have shown that microresonator-based Kerr optical frequency combs will become mainstream in the future.Two methods of pump frequency tuning and self-injection locking were used to obtain Kerr combs in the same silicon nitride microresonators with free spectral ranges of 50 GHz and 100 GHz.Singlesoliton combs are realized with both methods.Simplicity,pump power,spectrum bandwidth,conversion efficiency,and linewidth are compared and analyzed.Our results show that the advantages of pump frequency tuning are a wider spectrum and higher soliton power while the advantages of self-injection locking are simplicity,compactness,low cost,significant linewidth narrowing,and high conversion efficiency.

Generation of polarized electron beams through self-injection in the interaction of a laser with a pre-polarized plasma

Polarized electron beam production via laser wakefield acceleration in pre-polarized plasma is investigated by particlein-cell simulations.The evolution of the electron beam polarization is studied based on the Thomas±Bargmann±Michel±Telegdi equation for the transverse and longitudinal self-injection,and the depolarization process is found to be influenced by the injection schemes.In the case of transverse self-injection,as found typically in the bubble regime,the spin precession of the accelerated electrons is mainly influenced by the wakefield.However,in the case of longitudinal injection in the quasi-1D regime(for example,F.Y.Li et al.,Phys.Rev.Lett.110,135002(2013)),the direction of electron spin oscillates in the laser field.Since the electrons move around the laser axis,the net influence of the laser field is nearly zero and the contribution of the wakefield can be ignored.Finally,an ultra-short electron beam with polarization of 99%can be obtained using longitudinal self-injection.

Recent advances in laser self-injection locking to high-Q microresonators

The stabilization and manipulation of laser frequency by means of an external cavity are nearly ubiquitously used in fundamental research and laser applications. While most of the laser light transmits through the cavity, in the presence of some back-scattered light from the cavity to the laser, the self-injection locking effect can take place, which locks the laser emission frequency to the cavity mode of similar frequency. The self-injection locking leads to dramatic reduction of laser linewidth and noise. Using this approach, a common semiconductor laser locked to an ultrahigh-Q microresonator can obtain sub-Hertz linewidth, on par with state-of-the-art fiber lasers. Therefore it paves the way to manufacture high-performance semiconductor lasers with reduced footprint and cost. Moreover, with high laser power, the optical nonlinearity of the microresonator drastically changes the laser dynamics, offering routes for simultaneous pulse and frequency comb generation in the same microresonator. Particularly, integrated photonics technology, enabling components fabricated via semiconductor CMOS process, has brought increasing and extending interest to laser manufacturing using this method. In this article, we present a comprehensive tutorial on analytical and numerical methods of laser self-injection locking, as well a review of most recent theoretical and experimental achievements.

The Second Hochschild Cohomology Group for One-Parametric Self-Injective Algebras

In this paper, we determine the second Hochschild cohomology group for a class of self-injective algebras of tame representation type namely, which are standard one-parametric but not weakly symmetric. These were classified up to derived equivalence by Bocian, Holm and Skowroński in [1]. We connect this to the deformation of these algebras.

Batalin-Vilkovisky Structure on Hochschild Cohomology of Self-Injective Quadratic Monomial Algebras

We give a complete description of the Batalin-Vilkovisky algebra structure on Hochschild cohomology of the self-injective quadratic monomial algebras.

Locally Self-Injective Property of FI^(m)

We consider the locally self-injective property of the product FI^(m) of category FI of finite sets and injections.Explicitly,we prove that the external tensor product commutes with the coinduction functor,and hence preserves injective modules.As corollaries,every projective FI^(m)-module over a field of characteristic O is injective,and the Serre quotient of the category of finitely generated FI^(m)-modules by the category of finitely generated torsion FI^(m)-modules is equivalent to the category of finite-dimensional FI^(m)-modules.

Evaluating the management of anaphylaxis in US emergency departments:Guidelines vs.practice

BACKGROUND:Anaphylaxis is characterized by acute episodes of potentially life-threatening symptoms that are often treated in the emergency setting.Current guidelines recommend:1) quick diagnosis using standard criteria;2) first-line treatment with epinephrine;and 3) discharge with a prescription for an epinephrine auto-injector,written instructions regarding long-term management,and a referral(preferably,allergy) for follow-up.However,studies suggest low concordance with guideline recommendations by emergency medicine(EM) providers.The study aimed to evaluate how emergency departments(EDs) in the United States(US) manage anaphylaxis in relation to guideline recommendations.METHODS:This was an online anonymous survey of a random sample of EM health providers in US EDs.RESULTS:Data analysis included 207 EM providers.For respondent EDs,approximately 9%reported using agreed-upon clinical criteria to diagnose anaphylaxis;42%reported administering epinephrine in the ED for most anaphylaxis episodes;and <50%provided patients with a prescription for an epinephrine auto-injector and/or an allergist referral on discharge.Most provided some written materials,and follow-up with a primary care clinician was recommended.CONCLUSIONS:This is the first cross-sectional survey to provide "real-world" data showing that practice in US EDs is discordant with current guideline recommendations for the diagnosis,treatment,and follow-up of patients with anaphylaxis.The primary gaps are low(or no) utilization of standard criteria for defining anaphylaxis and inconsistent use of epinephrine.Prospective research is recommended.

Homological dimensions of gentle algebras via geometric models

Let A=kQ/I be a finite-dimensional basic algebra over an algebraically closed field k,which is a gentle algebra with the marked ribbon surface(SA,MA,ΓA).It is known that SAcan be divided into some elementary polygons{Δi|1≤i≤d}byΓA,which has exactly one side in the boundary of SA.Let■(Δi)be the number of sides ofΔibelonging toΓAif the unmarked boundary component of SAis not a side ofΔi;otherwise,■(Δi)=∞,and let f-Δbe the set of all the non-co-elementary polygons and FA(resp.f-FA)be the set of all the forbidden threads(resp.of finite length).Then we have(1)the global dimension of A is max1≤i≤d■(Δi)-1=maxΠ∈FAl(Π),where l(Π)is the length ofΠ;(2)the left and right self-injective dimensions of A are 0,if Q is either a point or an oriented cycle with full relations.masΔi∈f-Δ{1,■(Δi)-1}=max n∈f-F_(A)l(П),otherwise,As a consequence,we get that the finiteness of the global dimension of gentle algebras is invariant under AvellaGeiss(AG)-equivalence.In addition,we get that the number of indecomposable non-projective Gorenstein projective modules over gentle algebras is also invariant under AG-equivalence.

CoHopficity of Self-Injective Rings

It is shown that a self-injective ring R is coHofian ring if and only if R has stable range one. This answers the open problem 5 of Varadarajian in [9] for self- injective ring R,i.e.,Mn(R) is coHopfian for coHopfian ring R. As a consequence of we answer problem of Goodeal in the affirmative in [3], for self-injective regular rings.

Universal Deformation Rings of Modules over Self-injective Cluster-Tilted Algebras Are Trivial

Let k be a fixed algebraically closed field of arbitrary characteristic,let Λ be a finite dimensional self-injective k-algebra,and let ∨ be an indecomposable non-projective left Λ-module with finite dimension over k.We prove that if τΛ∨ is the Auslander-Reiten translation of ∨,then the versal deformation rings R(Λ,∨)and R(Λ,τΛ∨)(in the sense of F.M.Bleher and the second author)are isomorphic.We use this to prove that if Λ is further a cluster-tilted k-algebra,then R(Λ,∨)is universal and isomorphic to k.

Some Relations on Generalizations of Injective Rings

Some relations about the generalizations of self-injective ring: P-injective ring, GP-injective ring, AP-injective ring, simple-injective ring and n-injective ring are studied.

Simulation studies of laser wakefield acceleration based on typical 100 TW laser facilities

In this paper, 2-D Particle-In-Cell simulations are made for Laser Wakefield Accelerations （LWFA）. As in a real experiment, we perform plasma density scanning for typical 100 TW laser facilities. Several basic laws for self-injected acceleration in a bubble regime are presented. According to these laws, we choose a proper plasma density and then obtain a high quality quasi-monoenergetic electron bunch with a rms energy of more than 650 MeV and a bunch length of less than 1.5 μm.

Relatively Flat Envelopes

The aim of this paper is to investigate relatively flat envelopes. A necessary and sufficient condition is given for a relatively-finitely presented module to have a (mono-morphic or epic) relatively flat envelope. Then those rings are characterized whose every relatively-finitely presented module has a relatively flat envelope which coincides with its in-jective envelope. Some known results are obtained as corollaries.

Recent development of Faith conjecture

Is a semiprimary right self-injective ring a quasi-Frobenius ring？ Almost half century has passed since Faith raised this problem. He first conjectured “No” in his book Algebra II. Ring Theory in 1976, but changing his mind, he conjectured “Yes” in his article “When self-injective rings are QF： a report on a problem” in 1990. In this paper, we describe recent studies of this problem based on authors works and raise related problems.